Use of Chemical weapons after Syria: Still a Red Line? A case study on the use of chemical weapons by the Syrian Arab Republic and its consequences for the normative content of the prohibition of chemical weapons in arm

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Faculty of Law

Use of Chemical Weapons after Syria: Still a Red Line?

A case study on the use of chemical weapons by the Syrian Arab Republic and

its consequences for the normative content of the prohibition of chemical

weapons in armed conflicts

Anna Katharina Zimmer Student number: 12834963 Email: annazimmer123@yahoo.de

Master’s Thesis International and European Law: Public International Law Supervisor: Prof. Dr. T. D. Gill

Second Reader: Dr. Jeroen van den Boogaard 10 July 2020

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The use of chemical weapons in the Syrian conflict by the Assad regime led to calls for a unified international response in order to uphold the prohibition of chemical weapons, which is considered to be a cornerstone of the international legal order. This thesis examines the effects of the violations and the international reactions thereto regarding the normative content of the prohibition of chemical weapons. The international community has expressed concern that the norm prohibiting chemical weapons has been weakened due to the repeated violations and the lack of multilateral enforcement action. After the first attacks were confirmed, Syria acceded to the Chemical Weapons Convention as part of Framework on the Elimination of Syrian Chemical Weapons Programme between the US and Russia. However, this successful reinforcement of the norm did not stop the regime from the continued use of chemical weapons against its own population in multiple cases. The attacks were consistently condemned by different actors on the international plane, but multilateral actions were and are impossible due to the political divisions within organs of the international organisations, especially within the UNSC. Eventually, in 2017 the US intervened militarily and in 2018, the US/UK and France carried out airstrikes on Syria’s chemical weapons facilities, which were met with support by a large part of the international community. Syria itself (and Russia) has persistently denied the attacks with shifting versions of explanations: the attacks never happened, were carried out by terrorists or were staged. However, all these actions and reactions show that the norm prohibiting the use of chemicals weapons has never been denied and was upheld by the international community, even without multilateral enforcement actions.

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List of abbreviations

AJIL American Journal of International Law

Anx. Annex

Art. Article

BBC British Broadcasting Corporation

BYIL British Yearbook of International Law

CD Conference on Disarmament

cf. [confer] compare

CNN Cable News Network

CW Chemical Weapon

CWC Convention on the Prohibition of the Development,

Production, Stockpiling and Use of Chemical Weapons and on their Destruction

Doc Document

ECtHR European Court of Human Rights

ed/eds editor/editors

edn edition

eg [exempli gratia] for example

EJIL European Journal of International Law

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f./ff. and the following page(s)

FFM Organisation for the Prohibition of Chemical Weapons

Fact-Finding Mission

IAC International Armed Conflict

ibid. [ibidem] in the same place

ICL International Criminal Law

ICRC International Committee of the Red Cross

ICTY International Criminal Tribunal for the former

Yugoslavia

IHL International Humanitarian Law

IIT Organisation for the Prohibition of Chemical Weapons

Identification and Investigation Team

ILC International Law Commission

ISIL Islamic State of Iraq and Levant

JIM United Nations-Organisation for the Prohibition of

Chemical Weapons Joint Investigative Mechanism

NATO North Atlantic Treaty Organization

NGO Non-governmental Organisation

NIAC Non-international Armed Conflict

No. Number

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p./pp. page(s)

para/paras paragraph(s)

PRIF Peace Research Institute Frankfurt

RCA Riot Control Agent

Res Resolution

RS Rome Statute of the International Criminal Court

SIPRI Stockholm International Peace Research Institute

UK The United Kingdom of Great Britain and Northern

Ireland

UN United Nations

UNC United Nations Charter

UNGA United Nations General Assembly

UNSC United Nations Security Council

UNSG United Nations Secretary General

UNTS United Nations Treaty Series

US United States of America

v. [versus] against

VCLT Vienna Convention on the Law of Treaties

Vol Volume

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A. Introduction

“Should the international community fail to take action to hold accountable those responsible for confirmed use [of chemical weapons] we risk lasting damage to this international norm, which is critical to international peace and security.”1

The use of CWs in and especially by the Syrian Arab Republic has concerned the international community since 2012 and has put horrible pictures in our heads. When the former US President Barack Obama declared the possible use of CWs by Syria “a red line”2_{the question}

of suitable and effective response measures to such violations of international law emerged. First concrete evidence for a chemical attack in the Ghouta area of Damascus in August 2013 was discovered by an UNSG investigative mission.3_{These attacks caused condemnations from}

the international community.4_{The use of those weapons received much attention during the}

Syrian civil conflict as it causes an abhorrent way of suffering and dying. The estimates of victims of the chemical attacks in Syria vary on a large scale, first, because of the nature of CWs and their possible long-term damage and second, because next to the UN and OPCW investigative missions, investigations by NGOs and other States were carried out.5_These

investigations come to different outcomes regarding victims and number of chemical attacks.

1_{Colum Lynch, ‘Russia Stalls Western Push to Sanction Syria for Chemical Weapons Attacks’, Foreign Policy}

(27 October 2016) <https://foreignpolicy.com/2016/10/27/russia-stalls-western-push-to-sanction-syria-for-chemical-weapons-attacks/> accessed 16 June 2020.

2_{White House, Office of the Press Secretary, ‘Remarks by the President to the White House Press Corps’ (20}

August 2012) <https://obamawhitehouse.archives.gov/the-press-office/2012/08/20/remarks-president-white-house-press-corps> accessed 6 June 2020.

3_{UNGA/UNSC, ‘Report of the United Nations Mission to Investigate Allegations of the Use of Chemical}

Weapons in the Syrian Arab Republic on the alleged use of chemical weapons in the Ghouta area of Damascus’ (16 September 2013) UN Doc A/67/997-S/2013/553, paras 27 f.

4_{See eg: UNSC Res 2118 (27 September 2013) UN Doc S/RES/2118; League of Arab States: Lin Noueihed,}

‘Arab League blames Syria’s Assad for chemical attack’, Reuters (27 August 2013) <https://www.reuters.com/article/us-syria-crisis-league-idUSBRE97Q0NI20130827>; US: White House, Office of the Press Secretary, ‘Statement by the President on Syria’ (31 August 2013) <https://obamawhitehouse.archives.gov/the-press-office/2013/08/31/statement-president-syria>; both accessed 17 June 2020.

5_{See eg the UK had its own investigative mission: Joint Intelligence Organisation, ‘Syria: Reported Chemical}

Weapons Use’ (29 August 2013)

<https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/235094/J p_115_JD_PM_Syria_Reported_Chemical_Weapon_Use_with_annex.pdf> accessed 17 June 2020.

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However, in this thesis, I will draw my conclusions based on the official OPCW and UN reports. Further, the thesis will be limited on the use of CWs by the Syrian government and thus will not consider possible chemical attacks by non-State actors.

In August 2013 Syria was not a party to the CWC6_{and could therefore only violate customary}

IHL prohibiting the use of CWs according to Rule 74 ICRC customary law study.7_{The Geneva}

Gas Protocol8_{does not prohibit the use of CWs in internal conflicts. However, following these}

events, the Syrian Arab Republic acceded to the CWC on 14 September 20139_{as part of the}

agreement between the Russian Federation and the US on a Framework for the Elimination of Chemical Weapons in the Syrian Arab Republic.10_{Now the Assad regime would violate a clear}

and comprehensive norm of conventional international law if such an incident was to be confirmed again. Therefore, this accession was welcomed by the international community and was a positive development in the battle against CWs.Regrettably, it did not stop the Syrian government from using CWs again against its own civilian population. Several incidents of the use of CWs from the Assad regime in the Syrian Arab Republic were confirmed between 2014 and today.11_{Different mechanisms by the OPCW and UN were set up to establish facts}

surrounding allegations of the use of toxic chemicals and to identify the perpetrators of the attacks. However, the UNSC was not able to authorise any collective action under Chapter VII UNC12_{due to the veto of the Russian Federation as a permanent member of the Council. This}

failure to punish Syria on the international plane for its violations of international law led to a

6_{UNGA, Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical}

Weapons and on their Destruction (adopted 3 September 1992, entered into force 29 April 1997) 1975 UNTS

45.

7 _ICRC, _Studies _on _Customary _IHL, _Rule ₇₄

<https://ihl-databases.icrc.org/customary-ihl/eng/docs/v1_rul_rule74> accessed 6 June 2020.

8_{UN, Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of}

Bacteriological Methods of Warfare (adopted 17 June 1925, entered into force 8 February 1928)

<https://unoda-web.s3-accelerate.amazonaws.com/wp-content/uploads/assets/WMD/Bio/pdf/Status_Protocol.pdf> accessed 18 June 2020.

9_{UNSC Res 2118 (n 4) Anx. I.}

10_{OPCW, Executive Council, ‘Joint National Paper by the Russian Federation and the United States of America,}

Framework for Elimination of Syrian Chemical Weapons’ (17 September 2013) EC-M-33/NAT. 1, Anx.

11_{See eg OPCW, Technical Secretariat, ‘Second Report of the OPCW Fact-Finding Mission in Syria Key}

Findings’ (10 September 2014) S/1212/2014, para 29; OPCW, Technical Secretariat, ‘Report of the OPCW Fact-Finding Mission in Syria regarding the Incident of 16 September 2016 as reported in the Note Verbale of the Syrian Arab Republic Number 113 dated 29 November 2016’ (1 May 2017) S/1491/2017, para 6.3.

12_{UNGA, Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS}

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military intervention by the US in 2017 and a US/UK/France coalition intervention in 2018 which were justified on the basis that the Assad regime was using CWs against its own population.13

These actions und reactions regarding the repeated use of CWs lead to the following research question: What does the use of CWs in Syria between 2013 and today mean for the normative content of the prohibition of chemical weapons in armed conflicts? This question will be answered through four different chapters each of which will deal with a sub-question which is needed to answer the main research question.

In the first chapter the evolution of the norm prohibiting CWswill be considered in order to show whether there exists a comprehensive and strong norm prohibiting CWs under the CWC today. Since the Convention entered into force there have been no reported violations until the incidents in the Syrian Arab Republic started in 2013.

The second chapter will evaluate the relevant legal framework prohibiting CWs in armed conflicts for Syria, both in customary and conventional international law. What is the scope of obligations of the prohibition of CWs? Did Syria violate the relevant norms, especially the CWC?

The third chapter will analyse the international reactions concerning the use of CWs in Syria. It will deal with statements by Syria itself, reactions by other States and international organisations, such as the UN and the OPCW.In order to analyse the consequences of the use

13 _{White House, National Security &}_{Defense, ‘A Letter from the President to}_{the Speaker of the House of}

Representatives and the President Pro Tempore of the Senate’ (8 April 2017)

<https://www.whitehouse.gov/briefings-statements/letter-president-speaker-house-representatives-president-pro-tempore-senate/.>; White House, National Security & Defense, ‘Statement by President Trump on Syria’ (13 April 2018) <https://www.whitehouse.gov/briefings-statements/statement-president-trump-syria/>; Prime Minister’s Office, ‘UK Policy Paper, Syria Action – UK Government Legal Position’ (14 April 2018) <https://www.gov.uk/government/publications/syria-action-uk-government-legal-position/syria-action-uk-government-legal-position>; all accessed 17 June 2020; UNSC, Verbatim Record, 8233rd_{meeting (14 April}

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of CWs on Syria, it is crucial to understand how the international community reacted or not reacted to the attacks.

Finally, the last chapter will assess the consequences for the norm prohibiting CWs. The legal implications for the norm prohibiting CWs under treaty and customary law will be evaluated. Regarding the norm prohibiting chemical weapons under treaty law, the validity of the CWC after the repeated violations and international reactions thereto will be examined. Further, it will be assessed in how far the customary norm is now more comprehensive than before the Syrian situation. This will be followed by a discussion about the effects in a more practical sense, regarding the use of CWs in the future, as well as possible response measures from the international community.

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B. The evolvement of the norm prohibiting chemical weapons

In order to show the evolution of the norm prohibiting CWs, the three major international agreements of the last century will be considered. One of the first agreements regarding the prohibition of CWs in armed conflicts was the Declaration Concerning Asphyxiating Gases of the Hague Convention 189914_{. After the abhorrent chemical attacks during WWI, the Geneva}

Gas Protocolentered into force in 1928. However, at the latest after the Gulf War in the 1980s, it was clear that a comprehensive convention was needed which does not only prohibit the use, but also the production and possession of CWs and obliges States to eliminate all their CWs. Such a success was achieved when the CWC entered into force in 1997. Before the incidents in Syria between 2013 and today, there were no reported uses of CWs under the CWC.15

I. Declaration Concerning Asphyxiating Gases

Before the Hague Peace Conference of 1899 there was no norm prohibiting chemical agents as weapons because the 1874 Brussels Declaration16_{which banned the use of poison and poisoned}

weapons in Art. 13(a) never entered into force. However, in 1899 the Hague Peace Conference took place and resulted in the 1899 Hague Convention17_{which included four main sections and}

three additional declarations.

Declaration II Concerning Asphyxiating Gases prohibited “the use of projectiles the sole object of which is diffusion of asphyxiating or deleterious gases”18_{. Because of the wording of}

Declaration II of “the sole object”, a restrictive interpretation argued that if only the fumes of

14_{International Peace Conference, Declaration (IV, 2) Concerning Asphyxiating Gases (adopted 29 July 1899,}

entered into force 4 September 1900) <https://ihl-databases.icrc.org/applic/ihl/ihl.nsf/Article.xsp?action=openDocument&documentId=2531E92D282B5436C 12563CD00516149> accessed 18 June 2020.

15_{cf. UNSC Res 2209 (6 March 2015) UN Doc S/RES/2209, preamble.}

16_{Brussels Conference of 1874, Projects of an International Declaration concerning the Laws and Customs of}

War (adopted 27 August 1874) <https://ihl-databases.icrc.org/ihl/INTRO/135> accessed 30 June 2020.

17_{International Peace Conference, Convention (II) with respect to the Laws and Customs of War on Land and its}

annex: Regulations concerning the Laws and Customs of War on Land (adopted 29 July 1899, entered into

force 4 September 1900) <https://ihl-databases.icrc.org/ihl/INTRO/150> accessed 18 June 2020.

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an explosive cause death by asphyxiation, it would not be prohibited by the Declaration because it is not the “sole” object.19 _{The broad interpretation however argued that the Declaration}

should not be construed narrowly because it would not create new law but codify earlier condemnations of use of poisonous gases.20_{Additionally, the Hague Convention included a}

‘general participation clause’ which laid down that the provisions are only applicable in conflicts in which all the belligerents are parties to it.21_{Last, the Convention did only apply to}

armed conflicts between States, because in 1899 the concept of NIACs did not exist.

The Declaration did not prove to be very effective in banning CWs on the battlefield. WWI led to chemical attacks with terrible consequences: 124,200 tonnes of chlorine, mustard and other chemical agents were released and approximately 90,000 soldiers suffered painful deaths due to these CWs.22_{Germany as the main actor using those weapons tried to justify its actions on}

different grounds. First, it was argued that they did not employ projectiles but the gas was diffused through cylinders specifically designed for that purpose.23_{Second, it was claimed that}

the emission of the gases was not the “sole” purpose of the shells they used, but that the gases were emitted incidental to the explosion of the shell.24_{Thus, they followed the restrictive}

interpretation of the Hague Declaration and denied the illegality of their actions. This interpretative scope shows the flaws of the obligations under the Declaration.

II. Geneva Gas Protocol

These incidents during WWI and condemnations of the effects of CWs led to the negotiations of the Geneva Protocol of the Use in War of Asphyxiating, Poisonous or Other Gases and Biological Methods of Warfare, which entered into force in 1928. The Protocol was regarded

19_{Masahiko Asada, ‘A Path to a Comprehensive Prohibition of the Use of Chemical Weapons under International}

Law: From The Hague to Damascus’ (2016) 21(2) Journal of Conflict and Security Law 153, 155.

20_ibid.

21_{Art. 2 Hague Convention (II) (n 17). During WWI the Declaration concerning Asphyxiating Gases ceased to}

apply when the US joined the war in 1917.

22_{OPCW, ‘Fact Sheet I: Origins of the Chemical Weapons Convention and the OPCW’}

<https://www.opcw.org/about-us/history> accessed 6 June 2020.

23_{Asada (n 19) 156.}

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as one of the major steps towards the prohibition of CWs after WWI25_{and prohibits “the use}

in war of asphyxiating, poisonous or other gases and of all analogous liquids, materials or devices”. The Protocol, however, had some issues: Some aspects were legally unclear or not prohibited and were thus not always capable of banning CWs in a comprehensive way in practice.

1. Legal issues of the Geneva Gas Protocol

First, according to the wording of the protocol “the use in war” of poisonous gases is prohibited. Generally, the meaning of “war” is understood in a material sense and means now armed conflict.26_{However, it is questionable if that includes also internal armed conflicts or only}

conflicts occurring between two or more States. The term “war” has to be interpreted according to the general rules of treaty interpretation in Art. 31 VCLT27_{to assess if it encompasses an}

internal armed conflict. Historically, in 1925 no rules of IHL were applicable to NIACs and Common Art. 328_{introduced a minimum scope of protections during these conflicts only in}

1949.29_{Moreover, the UNGA Resolution 2603A (XXIV) from 1969 states that “the use in}

international armed conflict of any chemical agents of warfare as contrary to the generally

recognized rules of international law as embodied in the Geneva Protocol”30_{. This is of}

importance as the explicit applicability of the Protocol only to IACs has been reiterated twenty years after the first rules for NIACs were introduced. Systematically31_{, the wording of the}

25_{Thilo Marauhn, ‘Chemical Weapons and Warfare’, Rüdiger Wolfrum (ed), Max Planck Encylopedia of Public}

International Law (2nd _edn _OUP _published _online ₂₀₁₆₎ _para ₂₀

<https://opil.ouplaw.com/view/10.1093/law:epil/9780199231690/law-9780199231690-e264> accessed 6 July 2020.

26_{cf. Richard Reeve Baxter/Thomas Buergenthal, ‘Legal Aspects of the Geneva Protocol of 1925’ (1970) 64 AJIL}

854, 868; Asada (n 19) 163.

27_{UNGA, Vienna Convention on the Law of Treaties (adopted 23 June 1969, entered into force 27 January}

1980) 1155 UNTS 331.

28_{ICRC, Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the}

Field (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 31; ICRC, Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea

(adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 85; ICRC, Convention (III) relative

to the Treatment of Prisoners of War (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS

135; ICRC, Convention (IV) relative to the Protection of Civilian Persons in Time of War (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 287.

29_{Asada (n 19) 166 f.; Baxter/Buergenthal (n 26) 869.}

30_{UNGA Res 2603A (XXIV), ‘Question of chemical and bacteriological (biological) weapons’ (16 December}

1969) UN Doc A/PV.1836.

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Protocol that the State parties “agree to be bound as between themselves” is also in favour of the applicability of the Protocol only to the situations of IACs.32_{These conflicts occur between}

two or more States so that the Parties are prohibited to use any asphyxiating, poisonous or other gases against another State, but not in the situation of an internal armed conflict against a non-State actor.

However, the scope of the Protocol could have expanded through subsequent State practice pursuant to Art. 31(3)(b) VCLT. Iraq used CWs against its Kurdish population in 1988 in Halabja, which was the only confirmed incident of CWs in a NIAC (before Syria).33_Some

State parties claimed that these attacks were a violation of the Geneva Gas Protocol.34

However, this new practice must be of certain frequency and agreement of the practice by all Parties is needed and thus, these few Statements are not enough.35

Consequently, this interpretation confirms the inapplicability of the Protocol in NIACs.

Second, it is debated if the scope of prohibited weapons (“poisonous or other gases”) covers RCAs and herbicides.36_{Especially the US and Australia have argued that the Protocol does not}

prohibit the use of irritant chemicals and anti-plant chemicals.37_{Third, several major powers}

reserved the right to use CWs in respond to chemical attacks and to use CWs against States who had not joined the Protocol.38_{Last, the Protocol is limited to the prohibition of the use of}

32_{cf. Anne Lorenzat, ‘The Current State of Customary International Law with regard to the Use of Chemical}

Weapons in Non-International Armed Conflicts’ (2017) 56 The Military Law and the Law of War Review 349, 363; Sandesh Sivakumaran, The Law of Non-International Armed Conflict (OUP 2012) 394.

33_{UNSC, ‘Report of the mission dispatched by the Secretary-General to investigate allegations of the use of}

chemical weapons in the conflict between the Islamic Republic of Iran and Iraq’ (25 April 1988) UN Doc S/19823, paras 4, 17 ff.

34_{See eg EU: European University Institute, (1988) European Political Cooperation Documentation Bulletin 4(2),}

p. 92; UK: Geoffrey Marston, ‘United Kingdom Materials on International Law 1988’ (1988) BYIL 59, 579; Iran: UNSC, ‘Letter dated 17 March 1988 from the acting Permanent Representative of the Islamic Republic of Iran to the United Nations addressed to the Secretary-General’ (17 March 1988) UN Doc. S/19639.

35_{cf. Mark Eugen Villinger, Commentary on the 1969 Vienna Convention on the Law of Treaties (Martinus Nijhoff}

Publishers 2009) Art. 31, para 20.

36_{SIPRI, The Problem of Chemical and Biological Warfare, Vol 3 (Almqvist & Wiksell 1973) 41 ff.;}

Baxter/Buergenthal (n 26) 856 ff.

37_{See eg SIPRI (n 36) 48 f., 59 f.; Australia: UNGA, Official Record, 1704}th_{meeting of the First Committee (28}

November 1969) UN Doc A/C.1/PV.1704, paras 69 f.; US: UNGA, Official Record, 1717th_{meeting of the}

First Committee (10 December 1969) UN Doc A/C.1/PV.1717, paras 41, 47.

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CWs, but does not encompass the prohibition of the development, production and possession of CWs.

It is still important to note that the obligations under the Geneva Gas Protocol were stronger than those under the Hague Convention and it tried to close legal gaps: it prohibits the use of any lethal chemical agents in IACs. It was successful in preventing the use of CWs in eg WWII. However, there still have been confirmed uses of CWs after the Protocol entered into force.39

2. Uses of chemical weapons under the Geneva Gas Protocol

During the Vietnam War, the herbicide Agent Orange, which contained the chemical dioxin, was used on a large scale by the US.40_{As mentioned above, it is not clear if the use of herbicides}

is prohibited under the Geneva Gas Protocol. Further, the US had not yet ratified the Protocol and also denied the illegality of its actions under customary international law.41_{During the}

Cold War, both the US and the Soviet Union had an enormous stockpile of CWs.42_However,

the Geneva Gas Protocol did not prohibit the production and possession of CWs.

There was only one clear case of a violation of the Geneva Gas Protocol: large scale chemical attacks occurred during the Gulf War between Iran and Iraq in the 1980s.43_{Regarding the use}

of CWs against Iran, Iraq never tried to argue that this was outside of the Geneva Gas Protocol.44_{Regarding the above-mentioned incident in Halabja, when Iraq used CWs against}

its Kurdish population, these attacks were not covered by the Protocol as an internal situation

39_{OPCW, ‘Fact Sheet I’ (n 22).} 40_{SIPRI (n 36) 30, 59, 60.}

41_{cf. UNGA, Official Record, 1452}nd_{meeting of the First Committee (14 November 1966) UN Doc.}

A/C.1/SR.1452, para 39.

42_{OPCW, ‘History: Looking back helps us look forward’ <https://www.opcw.org/about-us/history> accessed 6}

June 2020.

43_{See eg UNSC, ‘Report of the specialists appointed by the Secretary-General to investigate allegations by the}

Islamic Republic of Iran concerning the use of chemical Weapons: Note by the Secretary-General’ (26 March 1984) UN Doc S/16433, paras 35 f.

44_{cf. Timothy L.H. McCormack, ‘International Law and the Use of Chemical Weapons in the Gulf War’ (1990)}

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and this was also claimed by Iraqi officials.45_{Concerning the international responses, the}

attacks in the Gulf War were condemned from the UNSC.46_{However, no international}

enforcement action was taken besides an investigation by the UNSG and the launch of economic sanctions (but no military action).47_{Moreover, Iraq was not named as the primarily}

responsible party by neither the UNSC nor the UNGA, even though there was only conclusive evidence from specialist reports regarding Iraq’s use of CWs, but not from Iran’s side.48

Consequently, in the past, the use of CWs was sometimes not prohibited under the relevant norms of international law or States interpreted the norms to justify their actions. There was only one case where the Geneva Protocol was undisputedly violated: during the Gulf War between Iraq and Iran. Especially this incident led to the negotiations of the CWC by the CD and finally to the signing of the CWC in 1993 in Paris.

III. Chemical Weapons Convention

With the CWC entering into force in 1997, a new era of prohibiting CWs under international law commenced. Pursuant to its preamble, the aim of the Convention is the complete elimination of an entire category of weapons of mass destruction. Regarding the scope of the Convention, it should be seen as complementing the obligations under the Geneva Gas Protocol, eg preamble and Art. XIII CWC.49_{Thus, the norm should be absolute in the fight}

against CWs and not as ambiguous as the norms were before in history. The vast majority of States are now parties to the Convention, excluding only Israel, Egypt, South Sudan and North

45_ibid.

46_{See eg UNSC Res 612 (9 May 1988) UN Doc S/RES/612, para 2; UNSC Res 620 (26 August 1988) UN Doc}

S/RES/620, para 1.

47_{cf. McCormack (n 44) 28 ff.; Richard Price, ‘Syria and the Chemical Weapons Taboo’ (2019) 4(1) Journal of}

Global Security Studies 37, 49.

48_{cf. UNSC, ‘Report of the mission dispatched by the Secretary-General to investigate allegations of the use of}

chemical weapons in the conflict between the Islamic Republic of Iran and Iraq’ (8 May 1987) UN Doc S/18852, para 65; UNSC Res 582 (24 February 1986) UN Doc S/RES/582, preamble; McCormack (n 44) 17, 20 ff.

49_{Walter Krutzsch, Eric Myjer, Ralf Trapp, ‘Introduction and General Issues’, Walter Krutzsch, Eric Myjer, Ralf}

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Korea rendering it a near universally accepted norm of international law.50_{Further, no State}

party has ever withdrawn from the Convention.

Importantly, the CWC entails the establishment of a special implementation body: the OPCW according to Art. VIII (1) CWC. This implementing body has several tasks: First, destroying all existing CWs under international verification. Second, monitoring the chemical industry to prevent new weapons from emerging. Third, providing assistance and protection to State Parties against chemical threats. Fourth, fostering international cooperation to strengthen implementation of the Convention and promote the peaceful use of the chemical industry.51

Moreover, the Conference of the State Parties as the principal organ of the OPCW can take measures in response to the use of CWs including sanctions in order to ensure compliance according to Art. XII CWC.

The first confirmed incidents of use of CWs after the CWC entered into force occurred in the Syrian Arab Republic in 2013/14.52_{Thus, between the Gulf War in the 1980s and the use of}

CWs in Syria, there have been no confirmed uses of CWs by States. The scope of obligations under the legal framework for Syria in both customary law and the CWC will be considered in the next chapter.

50_{OPCW, ‘Evolution of the Status of Participation in the Convention’}

<https://www.opcw.org/evolution-status-participation-convention> accessed 6 June 2020.

51_{OPCW, ‘About US: We want to live in a world free of chemical weapons’ <https://www.opcw.org/about-us>}

accessed 6 June 2020.

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C. Obligations under the current legal framework for Syria

In the Syrian Arab Republic CWs were used by a government against its own population in a NIAC. In how far is that prohibited under the current customary and treaty law?

In order to answer this question, first, the factual situation in Syria from 2013 until today regarding the use of CWs will be explained. Second, the prohibition of CWs in customary international humanitarian law will be evaluated, because the Assad regime used CWs before they acceded to the CWC.53_{Third, the violations of the CWC by Syria will be established.}

I. Situation in Syria

In 2012, the first allegations of use of CWs in Syria emerged. Subsequently, in March 2013, the UK and France requested the UNSG to open an investigation into the alleged use of CWs on 19 March 2013 in Aleppo and Damascus and Syria itself requested the UN to investigate the incident of 19 March 2013 in Aleppo.54

Then, on 21 August 2013, sarin rockets were used in the Ghouta area around Damascus on a large scale causing between 300 and 1700 deaths.55_{The Ghouta attacks entailed important}

consequences. First, the UNSG investigation team started to carry out investigations of these incidents which happened shortly after their arrival in Syria.56_{The team found that there was}

clear evidence that sarin rockets were used in the Ghouta area, also against civilians.57_This

mission lacked however a mandate to identify the perpetrator as it was their task to find out whether CWs had been used at all.58_{Second, Syria acceded to the CWC on 14 September 2013}

53_{UNGA/UNSC, A/67/997-S/2013/553 (n 3) paras 27 f.}

54_{Mechanism under the UNSG: UNGA Res 42/37C, ‘Measures to uphold the authority of the 1925 Geneva Gas}

Protocol and to support the conclusion of a Chemical Weapons Convention’ (30 November 1987) UN Doc A/RES/42/37C, para 4.

55_{See Introduction; BBC News, ‘Syria chemical attack: What we know’ (24 September 2013)}

<https://www.bbc.com/news/world-middle-east-23927399> accessed 8 June 2020.

56_{UNGA/UNSC, A/67/997-S/2013/553 (n 3) para 15.} 57_{ibid, paras 27 f.}

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as part of the agreement between the Russian Federation and the US on a Framework for the Elimination of Chemical Weapons in the Syrian Arab Republic in September 201359_and

therefore, the OPCW could now get involved. In October 2013, an OPCW-UN joint mission was established to oversee the elimination of Syria’s CWs program.60_{Again, this mission did}

not have the mandate to identify the perpetrator of the attacks. Third, the UNSC adopted Resolution 2118 condemning the use of CWs against civilians and stating that the use of CWs constitutes a serious violation of international law.61

However, those consequences did not prevent the Assad regime from using CWs again. In April 2014 the OPWC set up the FFM “to establish facts surrounding allegations of the use of toxic chemicals […] for hostile purposes in the Syrian Arab Republic”, again without the task to attribute responsibility.62_{The FFM found in its second report that chlorine as a weapon was}

used in different parts of Syria.63_{There have been several confirmed}64_{and alleged}65_incidents

between 2015 and 2018 by the FFM.The most recent incident where the FFM concluded that there were reasonable grounds to believe that chlorine as a CW was used happened in Douma in April 2018.66_{In order to identify the perpetrator of the chemical attacks confirmed by the}

FFM, the JIM was established under the UNSC in August 2015.67_{After its mandate expired in}

November 2017, the OPCW set up the IIT in 2018.68_{In August 2016, the Syrian government}

59_{OPCW, EC-M-33/NAT. 1 (n 10) Anx.}

60_{OPCW, Executive Council, ‘Destruction of Syrian Chemical Weapons’ (27 September 2013) EC-M-33/DEC.1.} 61_{UNSC Res 2118 (n 4) preamble.}

62_{OPCW, Technical Secretariat, ‘Summary Report of the Work of the OPCW Fact-Finding Mission in Syria}

covering the period from 3 May to 31 May 2014’ (16 June 2014) S/1191/2014, para 1.

63_{See eg OPCW, S/1212/2014 (n 11) para 29.} 64_{See eg ibid; OPCW, S/1491/2017 (n 11) para 6.3.}

65_{See eg OPCW, Technical Secretariat, ‘Report of the OPCW Fact-Finding Mission in Syria regarding alleged}

incidents in Ltamenah, the Syrian Arab Republic 24 and 25 March 2017’ (13 June 2018) S/1636/2018, para 6.8 f.; OPCW, Technical Secretariat, ‘Report of the Fact-Finding Mission regarding the incident of alleged use of toxic chemicals as a weapon in Douma, Syrian Arab Republic, on 7 April 2018’ (1 March 2019) S/1731/2019, para 9.12.

66_{OPCW, S/1731/2019 (n 65) para 9.12.}

67_{UNSC Res 2235 (7 August 2015), UN Doc S/RES/2235, para 6; UNSC Res 2319 (17 November 2016) UN}

Doc S/RES/2319, para. 1.

68_{OPCW, Conference of the State Parties, ‘Decision addressing the Threat from Chemical Weapons Use’ (27}

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was first officially identified as a perpetrator of using chlorine bombs as CWs.69_{The situation}

is thus different than Iraq: the Syrian Government was named as the primarily responsible party by the JIM and the IIT in their reports.70

II. Customary law prohibiting chemical weapons

As mentioned above, the UNSC stated after the Ghouta attacks in August 2013 that the “use of chemical weapons constitutes a serious violation of international law”71_{. Back in 2013, when}

Syria used CWs for the first time, the conflict was occurring between the Syrian government and organised armed groups and thus of non-international character.72_{The Geneva Gas}

Protocol is not applicable in NIACs and Syria was not a member of the CWC in August 2013 and therefore, the statement can only refer to a violation of customary international law. Customary international law requires widespread and consistent State practice, which must be supported by opinio juris.73

Rule 74 of the ICRC studies of customary international humanitarian law establishes that there is a norm prohibiting CWs in both IACs and NIACs.74_{Regarding the above-mentioned}

evolution of the norm prohibiting CWs, a customary norm prohibiting chemical agents in IACs has definitely developed. But was there really enough evidence supporting a prohibition of CWs in NIACs before the Ghouta attacks?

69_{UNSC, ‘Letter dated 24 August 2016 from the Secretary-General addressed to the President of the Security}

Council’ (24 August 2016) UN Doc S/2016/738, paras 52 ff.

70_{cf. ibid; UNSC, ‘Letter dated 21 October 2016 from the Secretary-General addressed to the President of the}

Security Council’ (21 October 2016) UN Doc S/2016/888, paras 25 ff.; OPCW, Technical Secretariat, ‘First Report by the OPCW Investigation and Identification Team pursuant to Paragraph 10 of Decision C-SS-4/DEC.3 “Addressing the Threat from Chemical Weapons use” Ltamenah 24, 25, and 30 March 2017’ (8 April 2020) S/1867/2020, para 9.28.

71_{UNSC 2118 (n 4) preamble.}

72_{Prosecutor v. Tadić, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, ICTY-94-1 (2}

October 1995) para 70; Masahiko Asada (n 19) p. 154; ICRC, ‘Syria: ICRC and Syrian Arab Red Crescent Maintain Aid Effort amid Increased Fighting’ (17 July 2012) <http://www.icrc.org/en/doc/resources/documents/update/2012/syria-update-2012-07-17.htm> accessed 17 June 2020.

73_{North Sea Continental Shelf (Federal Republic of Germany v. Denmark and the Netherlands), Judgment, ICJ}

Reports 1969, p. 3, paras 70 ff.

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On the one hand, it has been argued that the State practice and opinio juris concerning the use of CWs in NIACs before the incidents in Syria have been ambiguous and therefore do not serve as proof for such a norm under custom.75_{It should not solely be relied on the ICRC studies}

which is criticised as being too progressive in developing customary humanitarian law.76_In

State practice, there has only been one confirmed incident of use of CWs in an internal conflict: the use of CWs by Iraq against its Kurdish population.77 _{Regarding this incident, there have}

been unclear statements, such as the UNSC Resolution 612 which condemned “the continued use of chemical weapons in the conflict between the Islamic Republic of Iran and Iraq contrary to the obligations under the Geneva Protocol”78_{. It is not clear whether this relates to the}

chemical attacks by Iraq to the Kurdish population in a NIAC situation. Further, it only mentions the Geneva Gas Protocol, but not customary international law.79_{Additionally, a}

statement was made by the German representative in the UNGA in which he referred to both the use of CWs between Iran and Iraq and the use of CWs of Iraq against the Kurdish population and described them as “breaches of the Geneva Protocol of 1925 and other norms of international law”80_{. This statement does not only relate to the internal situation, does not}

mention customary international law and could refer to violations of Common Art. 3 or AP II.81

On the other hand, there is strong support in State practice and opinio juris supporting Rule 74 ICRC customary law studies. Evidence for this can be found in several international and national documents. The ICTY stated already in 1995 that there is a consensus between the international community that those weapons are prohibited in internal armed conflicts.82

This approach was also claimed by the ECtHR in 2010.83 _{In ICL, the use of asphyxiating or}

75_{cf. Asada (n 19) 188 ff.} 76_{cf. Lorenzat (n 32) 357.}

77_{UNSC, S/19823 (n 33) paras 4, 17 ff.} 78_{UNSC Res 612 (n 46) para 2.} 79_{Lorenzat (n 32) 363.}

80_{UNGA, Verbatim Record, 43}rd_{session, 31}st_{meeting of the First Committee (9 November 1988) UN Doc}

A/C.1/43/PV.31, p. 16.

81_{ICRC, Protocol Additional (II) to the Geneva Conventions of 12 August 1949, and relating to the Protection of}

Victims of Non-International Armed Conflicts (adopted 12 December 1977, entered into force 8 June 1977)

1125 UNTS 609.

82_{Prosecutor v. Tadić (n 72) para 124.}

83_{van Anraat v. The Netherlands, Third Section as to the Admissibility of Application No. 65389/09 ECHR (6}

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poisonous gases in NIACs constitutes a war crime pursuant to Art. 8(2)(e)(xiv) RS84_{and the}

RS had 120 parties in 2013. Additionally, in 2013, 190 States were parties to the CWC, and Art. I CWC prohibits the use of CWs “under any circumstances” and thus also in internal armed conflicts.85_{Colombia’s constitutional court explicitly held that the prohibition of the use of}

CWs in NIACs is part of customary international law.86_{Further, there have been statements}

that CWs should never be used, which includes the use in NIACs, such as after the chemical attacks in Iraq against the Kurds, the UK officially stated it “condemns unreservedly this and all other uses of chemical weapons”.87_{Sweden stressed that the attacks on Halabja were a gross}

violation of customary international law.88_{This serves as evidence for the fact that in 2013 the}

vast majority of States were of the opinion that CWs are a prohibited method of warfare in NIACs.

Consequently, the stronger arguments are in favour of a rule of customary law prohibiting CWs in NIACs and therefore for a violation of international law by the Syrian Arab Republic.

III. Treaty law

1. Geneva Gas Protocol

Next to violations of customary international law, Syria could have violated the Geneva Gas Protocol. However, regarding the Syrian conflict in 2013 and its character as non-international, the Protocol is not applicable.89_{Hence, Syria did not violate the Protocol when using sarin}

rockets in August 2013 during the Ghouta attacks.

84_{UNGA, Rome Statute of the International Criminal Court (adopted 17 July 1998, entered into force 1 July}

2002) 2187 UNTS 3; cf. North Sea Continental Shelf (Federal Republic of Germany v. Denmark and the

Netherlands), Judgement, ICJ Reports 1969, p. 4, paras 70 ff.

85_{Will be assessed below, C. III. 2.}

86_{Constitutional Court of Colombia, Constitutional Case No. C-225/95, Judgment (18 May 1995) para 23}

<https://casebook.icrc.org/case-study/colombia-constitutional-conformity-protocol-ii> accessed 19 June 2020.

87_{Marston (n 34) 579.}

88_{UNGA, Official Records, Fifteenth Special Session, 2}nd_{Plenary meeting (1 June 1988) UN Doc. A/S-15/PV.2,}

para 89.

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2. Chemical Weapons Convention

The following part will assess to what extent Syria’s continued use of CWs was prohibited under the CWC. The question is: does the Convention apply in NIACs and does it prohibit the use of the chemical’s sarin and chlorine? The scope of the Convention is enshrined in Arts. I and II CWC: Art. I CWC lays down the prohibited behaviour and Art. II CWC defines what CWs are. The CWC complements the Geneva Gas Protocol in different ways, three of them will be explained in the following in relation to the Syrian situation.

The general obligations and prohibitions under the CWC are set out in Art. I CWC. It is prohibited for the State parties to develop or to use CWs or to engage in any military preparation to use CWs or to assist in any of these prohibited activities under any circumstances according to Art. I(a)-(d) CWC. The wording of “never under any circumstances” relates to the first extension, the applicability of the CWC in NIACs. It gives the impression that the CWC prohibits the use of CWs in both IACs and NIACs.90_{However, the US, who originally proposed}

the wording of “never under any circumstances” expressed the view in the CD in 1991 that the use of CWs under the CWC would be prohibited “against any State”91_{. The wording of “against}

any State” implicates that the Convention might not necessarily be applicable during internal armed conflicts. It would then not be prohibited to use CWs in an internal situation, against armed groups or the civilian population.

On the contrary, the ICRC is of the opinion that the expression “any circumstances” includes the applicability of the Convention in NIACs.92_{This broad understanding of Art. I (1) CWC is}

supported by the fact that in 1997 rules of IHL existed also for NIACs, especially Common Art. 3 and AP II. In the period following the Cold War, the incidence and scale of NIACs has increased steadily. Consequently, there has been a movement in the direction of applying norms

90_{cf. Natalino Ronzitti, ‘Assessment of the 1993 Chemical Convention: Light and Shadow’ Giovanni}

Gasparini/Natalino Ronzitti (eds), The Tenth Anniversary of the CWC’s Entry into Force: Achievements and

Problems (Istituto Affari Internazionali, 2007) 36.

91_{CD, ‘Letter dated 22 May 1991 from the Acting Representative of the United States of America Addressed to}

the President of the Conference on Disarmament Transmitting a Statement Issued by the President of the United States of America Concerning the United States Initiative for Completing the Negotiations on a Chemical Weapons Convention’ (23 May 1991) CD/1007, p. 4, para 4.

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that were originally intended for IACs to internal armed conflicts.93_{Further, the UNSC stated}

in its Resolutions 2209 and 2235 that any use of CWs by Syria would be a violation of the CWC.94_{Thus, the prohibition of the use of CWs under the CWC is applicable in NIACs and}

to the conflict in Syria.

Second, Art. II CWC sets out the definition of CWs. Pursuant to Art. II (1) (a) CWC, CWs are “toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention and as long as the types and quantities are consistent with such purposes”. This is also referred to as the ‘general-purpose criterion’95_{. The purposes which} _{are no prohibited}

under the Convention are listed in Art. II (9) CWC and include, inter alia, industrial, pharmaceutical, protective, and law enforcement purposes. Argumentum e contrario, the purpose of the use in armed conflict is prohibited under the Convention.Hence, there is no list of what exactly constitutes a CW, just the Annex on Chemicals to the Convention which is used for routine declaration and verification purpose.96_{However, toxic chemicals which are}

not listed in the Annex can be CWs pursuant to Art. II (1) CWC.97_{According to}

Art. II (2) CWC “toxic chemicals” are all chemicals which cause death, temporary incapacitation or permanent harm to humans or animals through their chemical action on life.

Sarin, which was used in the Syrian armed conflict,is listed in the Annex on Chemicals98_{, was}

used against the civilian population in an armed conflict and is therefore a prohibited toxic chemical according to Art. II (1) (a) CWC. This is different regarding chlorine because it has not been listed in the Annex to the Convention. The use of chlorine is very common for

93_{cf. Prosecutor v. Tadić (n 72) paras 70 ff.; ICRC, Studies on Customary IHL (n 7).} 94_{UNSC Res 2209 (n 15) para 2; UNSC Res 2235 (n 67).}

95_{Graham S Pearson/Malcolm R Dando (eds), ‘Implementation of the General Purpose Criterion of the Chemical}

Weapons Convention’, First CWC Review Conference Paper No. 3, Department of Peace Studies of the University of Bradford (2003) <https://www.brad.ac.uk/acad/scwc/cwcrcp/cwcrcp_3.pdf> accessed 6 June 2020.

96_{Walter Krutzsch/Ralf Trapp, ‘Article II: Definitions and Criteria’, Walter Krutzsch, Eric Myjer, Ralf Trapp}

(eds) The Chemical Weapons Convention: A Commentary (OUP 2014) 76.

97_ibid.

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legitimate industrial use and is thus a so called ‘dual-use chemical’.99_{When used against human}

beings, chlorine causes death by suffocating as well as lifelong damage to the lungs and other vital organs.100 _{It is a toxic chemical and was used for the prohibited purpose of an armed}

conflict in Syria. Thus, it is captured by Art. II (1) (a) CWC.

Third, the CWC does not only prohibit the use of CWs but also the production and possession of CWs pursuant to Art. I(1)(a) CWC. Further, it obliges every party to destroy all CWs according to Art. I (2) CWC.Therefore, Syria was under the obligation to destroy all its CWs after they joined the CWC.

Moreover, law enforcement, including domestic riot control against the civilian population is a purpose not prohibited under the Convention according to Art. II (9) (d) CWC. Thus, RCAs with an irritating effect (Art. II (7) CWC) are allowed for domestic riot control.101_{However, if}

they are applied as a method of warfare, which is synonymous with the ‘use in armed conflict’, RCAs will be prohibited CWs pursuant to Art. I (5) CWC.102_{Consequently, all chemicals are}

now definitely prohibited for the purpose of the use in armed conflicts and therefore in the Syrian conflict.

Under the CWC a comprehensive norm regulating the use of CWs in both IACs and NIACs has evolved. It prohibits the use of toxic chemicals for the purposes of armed conflicts and obliges the State parties to destroy all those CWs. Hence, Syria violated Art. I(1)(a) and (b) when they used sarin and chlorine bombs against its own population from 2013 onwards. After such a case of confirmed noncompliance, the aim of the OPCW is to restore compliance as

99_{Krutzsch/Trapp (n 96) 76.}

100_{cf. WHO Report on Health Aspects of Chemical and Biological Weapons, Report of a WHO Group of}

Consultants (28 November 1969) Anx. 4, 25ff.

<https://apps.who.int/iris/bitstream/handle/10665/39444/24039.pdf;jsessionid=1C3496F2E583BBF2CEB86 6918EF48071?sequence=1> accessed 21 June 2020.

101_{Price (n 47) 38.}

102_{Walter Krutzsch, ‘Article I: General Obligations’, Walter Krutzsch, Eric Myjer, Ralf Trapp (eds) The Chemical}

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quickly as possible, Art. XII CWC. Regarding the situation in Syria, different mechanisms by the OPCW were/are still in place to investigate the incidents and eventually to attribute responsibility. Consequently, it seems that a successful and strong norm of international law in the fight against weapons of mass destruction has been developed. The question is, if this strong prohibition changed because of the repeated violations of the CWC in Syria and the international reactions thereto?

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D. International reactions to the use of chemical weapons in Syria

The repeated use of CWs in Syria did not remain unanswered by the international community. The chemical attacks have been condemned by States, the UN and the OPCW. However, the UNSC was not able to take any collective enforcement action because of the veto power of the Russian Federation. As has been pointed out above, the OPCW took enforcement actions and controlled the destruction of the CWs in Syria as well as investigated the incidents. Further, unilateral military actions were taken by other States to enforce the prohibition of CWs. These different actions will be analysed in the following chapter.

First, the action and statements by Syria itself will be considered, from its accession to the CWC in September 2013 to its official statements on the use of CWs in the Syrian conflict. Second, the reactions by other States will be evaluated, especially the US/UK/France military intervention in 2018. Third, statements and institutional measures taken by the international organisationsof the UN and the OPCW will be examined.

I. Actions by Syria

1. Syria’s accession to the Chemical Weapons Convention

After the sarin attacks in Ghouta in August 2013, Syria joined the CWC and was thus obliged to destroy all CWs. The Syrian foreign minister stated on 10 September 2013 that the government would agree to a deal to join the CWC, declare its CWs materials and submit Syrian facilities to inspection.103_{The accession was part of the US Russia Framework on the}

elimination of Syrian CWs. The aim of the framework was the destruction of Syrian CWs in the soonest and safest way possible to reduce the threats posed to the Syrian people.104_{It even}

contained the provisional application of the CWC for Syria from 14 September 2013 onwards, while the CWC only entered into force for Syria on 14 October 2013. Moreover, Syria made

103_{Price (n 47) 42.}

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the declaration covering its CWs program105_{pursuant to Art. III CWC, and this development}

was an important step in the chemical disarmament process.

Regarding the enforcement of the prohibition of CWs, the accession of Syria to the CWC constitutes a successful chain of events.106_{The norm was reinforced only a month after the}

Ghouta attacks in August 2013 and Syria’s violation of customary law illustrated above.107

Further, Syria is now obliged to comply with the obligations under the CWC and the OPCW was allowed to oversee the dismantling and destruction of Syria’s CWs capability. The international condemnations and pressure on Syria were crucial steps in binding Syria to the comprehensive obligations under the CWC. It is of importance that Syria did not join the CWC on its own accord, but as part of a deal between third States, which also constitutes a way of enforcing international law.Hence, this action strengthened the prohibition of CWs.

2. Denial of use of chemical weapons

However, despite its adherence to the CWC Syria used CWs again and did not comply with its obligations under the CWC. Regarding the alleged and confirmed incidents of chemical attacks, Syria has repeatedly denied the use of CWs and thus never accepted responsibility for any of the attacks. Starting after the first allegations of use of CWs, the Syrian foreign minister stated in July 2012 that “no chemical or biological weapons will ever be used”108_{. In August}

2013, after the attacks in Ghouta, Assad denied the use of CWs and he maintained this position in the form of shifting versions of denials: no attack happened at all, the victims were killed by rebels or the attack was staged.109_{Moreover, the impartiality and integrity of the OPCW}

mechanisms and reports were called into question. It was claimed that the 2016 JIM report

105_{OPCW, EC-M-33/DEC.1 (n 60) para. 1.} 106_{cf. Price (n 47) 42.}

107_{See C. II.}

108_{Ian Black, ‘Syria insists chemical weapons would only be used against outside forces’ The Guardian (24 July}

2012) <https://www.theguardian.com/world/2012/jul/23/syria-chemical-weapons-own-goal> accessed 6 June 2020.

109_{cf. Price (n 47) 46; UNSC, ‘Letter dated 10 October 2016 from the Permanent Representative of the Syrian}

Arab Republic to the United Nations addressed to the President of the Security Council’ (10 October 2016) UN Doc S/2016/844, pp. 3 ff.; BBC News, ‘Syria Chemical Attack “fabricated” – Assad’ (13 April 2017) <https://www.bbc.com/news/world-middle-east-39588876> accessed 18 June 2020.

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identifying the Syrian government as the perpetrator was unprofessional and politicised.110_The

denial was based inter alia on the argument that CWs were not effective on the field compared to conventional weapons, hence, there was no reason why Syria would use them.111_{Even after}

the chemicalattacks in Idlib in April 2017 (which was subsequently attributed to the Syrian government by the JIM112_{), the Assad regime stated “the Syrian army has not, did not, and will}

not use this kind of weapon”113_{. It further claimed that the accusations of the Syrian use of CWs}

were launched by countries known for their hostility towards the Syrian government.114

Consequently, the repeated denial of use of CWs by Syria has important legal implications: The Syrian government knows that there is a strong and comprehensive norm prohibiting the use of CWs against the own population and it accords significant importance to this norm.115

It was undoubtedly aware of the fact that the use of those weapons would be a violation of international law.

3. Possible justifications

As seen above, States sometimes tried to justify the use of CWs by interpreting the treaty rules in the past.116_{However, the Syrian government did neither attempt to justify the violation as}

an exception to the norm nor did it try to redefine what could count as a violation.117_There

would have been different possibilities: Syria could have referred to the use of chemicals as possible law enforcement according to Art. II (9) (d) CWC or argued for a possible legitimate

110_{cf. UNSC, S/2016/844 (n 109) pp. 4 ff.} 111_ibid.

112_{UNSC, ‘Letter dated 26 October 2017 from the Secretary-General to the President of the Security Council’ (26}

October 2017) UN Doc S/2017/904, para 46.

113 _Aljazeera, _‘Syria _denies _using _chemical _weapons _in _Idlib’ ₍₆ _April ₂₀₁₇₎

<https://www.aljazeera.com/news/2017/04/syria-denies-chemical-weapons-idlib-170406103242116.html> accessed 6 June 2020.

114_ibid.

115_{Una Becker-Jakob, ‘Countering the Use of Chemical in Syria: Options for Supporting International Norms and}

Institutions’ (2019) 63 Non-Proliferation and Disarmament Papers 1, 11.

116_{See B. II. 2.} 117_{Price (n 47) 41.}

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use of certain kinds of chemicals in armed conflicts, or that there is an exception for use of CWs against terrorists or defend the use of CWs as an exception in extremis.118

An interpretative scope can be proof of the weakness of treaty rules, as the cases of CWs in the past have shown. The lacking justification and interpretation by Syria show that the CWC contains a comprehensive rule of international law without any legal gaps. This is probably the reason why the Syrian government used a different kind of defence: as mentioned above, it claimed that the conducted investigations were politicised and unprofessional and blamed rebels to have used CWs. Hence, the Syrian government just shifted the burden of proof to its accusers and did not have try find a new justification for its use of CWs (which would probably have been unsuccessful). Such denial can be more effective than legal justification.

II. Reactions by other States

1. Reactions in the run up to the US/UK/France intervention

The use of CWs in Syria has been universally condemned by other States.119_{Before the sarin}

attacks in Ghouta, former US President Obama declared the possible use of CWs by the Syrian regime a “red line”, considering using force if such an incident would be confirmed.120

However, after the confirmed use of sarin gas in Ghouta in 2013 the US did not take any action and hence, this sole diplomatic response did not prevent the use of CWs.After Syria joined the CWC but continued to use CWs, States condemned those attacks, explicitly mentioned the illegality of Syria’s behaviour under international law and called for the accountability for the

118_{Price (n 47) 48.}

119_{See eg: Canada: Bruce Campion-Smith ‘Stephen Harper urges military action against Syria’ Toronto Star (7}

September 2013)

<https://www.thestar.com/news/canada/2013/09/06/stephen_harper_urges_military_action_against_syria.ht ml>; Australia: David Wroe ‘Kevin Rudd discussed Syria crisis with Barack Obama’ The Sydney Morning

Herald (27 August 2013)

<http://www.smh.com.au/federal-politics/federal-election-2013/kevin-rudd-discussed-syria-crisis-with-barack-obama-20130827-2sn22.html>; Turkish Ministry of Foreign Affairs of Turkey, Press Release Regarding the Attacks Perpetrated by the Forces of the Regime in Various Neighborhoods of Damascus in Syria (21 August 2013) <http://www.mfa.gov.tr/no_-231_-21-august-2013_- press-release-regarding-the-attacks-perpetrated-by-the-forces-of-the-regime-in-various-neighborhoods-.en.mfa>; Vietnamese Ministry for Foreign Affairs, ‘Remarks by Foreign Ministry Spokesman Luong Thanh

Nghi on Syria’s situation’ (29 August 2013)

<http://www.mofa.gov.vn/en/tt_baochi/pbnfn/ns130904232638>; all accessed 8 June 2020.

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human rights abuses.121_{The US even carried out a unilateral military intervention in Syria in}

April 2017 as a response to chemical attacks in Idlib which it attributed to the Syrian government.122_{The intervention received support from a part of the international}

community.123

However, especially Russia criticised the condemnations and the US military intervention, claiming that these were based on sole allegations by Western States.124_{Russia as an ally of}

Syria maintained the position that Syria was not behind the attacks.125_{Like Syria itself, they}

did not argue that the attacks were legal under international law, eg by claiming a new exception to the use of CWs under the CWC. Hence, neither Syria or other States denied or rejected the norm prohibiting CWs itself.

2. US/UK/France military intervention 2018

The reactions by States became stronger after chlorine attacks in April 2018 in Douma126_were

carried out. Subsequently to the attacks, other States, inter alia, the EU, the US, the UK, France and Turkeycondemned the use of CWs in the strongest terms and called for aresponse by the international community.127_{These developments led to more unilateral enforcement actions by}

States. In April 2018, the US, the UK and France carried out airstrikes targeting Syrian CWs

121_{See eg: Spanish Ministry for Foreign Affairs and Cooperation, Official Statement 030, ‘Condemnation of use}

of chemical weapons in Syria’ (14 April 2020)

<http://www.exteriores.gob.es/Portal/en/SalaDePrensa/Comunicados/Paginas/2020_COMUNICADOS/2020 0414_COMU030.aspx>; German Ministry for Foreign Affairs, ‘Außenminister Maas erinnert an Giftgasangriffe in Syrien’ (4 April 2019) <https://www.auswaertiges-amt.de/de/newsroom/maas-giftgasangriffe-syrien/2207268>; all accessed 8 June 2020.

122_{Letter from the US President (n 13).}

123_{See eg: Germany/France: Presse- und Informationsamt der Bundesregierung, ‘Joint Statement by Federal}

Chancellor Merkel and President Hollande of France following the air strikes in Syria’ (7 April 2017) <https://archiv.bundesregierung.de/archiv-de/meta/startseite/joint-statement-by-federal-chancellor-merkel-and-president-hollande-of-france-following-the-air-strikes-in-syria-442858>; Turkish Ministry for Foreign Affairs, ‘Press Release Regarding the USA Military Operation Targeting the Syrian Regime’s Shayrat Airbase in Homs’ (7 April 2017) <http://www.mfa.gov.tr/no_107_-7-april-2017_-press-release-regarding-the-us_-military-operation-targeting-the-syrian-regime_s-shayrat-airbase-in-homs.en.mfa>; NATO Secretary General, ‘Statement by NATO Secretary General Jens Stoltenberg on US strikes in Syria’ (7 April 2017) <https://www.nato.int/cps/en/natohq/news_143082.htm>; all accessed 18 June 2020.

124_{Samira Said/Ashley Fantz, ‘Syrian activists: Video show chemical weapons used’ CNN (22 August 2013)}

<https://edition.cnn.com/2013/08/21/world/meast/syria-civil-war/index.html> accessed 8 June 2020.

125_{Deutsche Welle, ‘EU calls for international response after suspected chemical attacks in Syria’ (8 April 2018)}

<https://www.dw.com/en/eu-calls-for-international-response-after-suspected-chemical-attack-in-syria/a-43300413> accessed 8 June 2020.

126_{OPCW, S/1731/2019 (n 65) para 9.12.} 127_{cf. Deutsche Welle (n 125).}

Use of Chemical weapons after Syria: Still a Red Line? A case study on the use of chemical weapons by the Syrian Arab Republic and its consequences for the normative content of the prohibition of chemical weapons in arm

Faculty of Law