Introduction

The Syrian civil war, which began in 2011 and escalated into one of the most destructive conflicts of the 21st century, has been marked by documented uses of chemical weapons — violations of some of the oldest and most universally accepted prohibitions in the laws of armed conflict. Understanding what happened, who was responsible, and why accountability has remained so elusive is essential for anyone studying the intersection of modern warfare and international law.

What Are Chemical Weapons and Why Are They Prohibited?

Chemical weapons are defined under the Chemical Weapons Convention (CWC) — a treaty with near-universal membership — as toxic chemicals and their precursors, munitions, and delivery systems designed to cause harm through chemical action. Their use in armed conflict has been prohibited since the 1925 Geneva Protocol, and the CWC, which entered into force in 1997, extended this to a comprehensive ban on production, stockpiling, and use.

Syria acceded to the CWC in 2013, following international pressure after a large-scale sarin attack in the Ghouta suburbs of Damascus that year. Accession was partly brokered as an alternative to threatened US military strikes.

Key Incidents

Investigations by the UN and the Organisation for the Prohibition of Chemical Weapons (OPCW) have documented multiple chemical attacks in Syria. The most significant include:

  • Ghouta, August 2013: A large-scale sarin attack on civilian areas east and west of Damascus. The UN confirmed sarin use; debate over attribution persisted but subsequent investigations pointed to Syrian government forces.
  • Khan Shaykhun, April 2017: A sarin attack on a town in Idlib province killed dozens of civilians, including children. The UN-OPCW Joint Investigative Mechanism attributed the attack to Syrian Air Force forces loyal to President Assad.
  • Douma, April 2018: Chlorine was allegedly used in cylinder-bomb attacks on a besieged enclave near Damascus. OPCW investigations found "reasonable grounds" to believe chlorine-containing substances were used as weapons; a later OPCW Investigation and Identification Team (IIT) attributed the attack to Syrian Arab Air Force.

The Accountability Gap

Despite extensive documentation, achieving formal accountability for chemical weapons use in Syria has been repeatedly blocked. The primary mechanism by which the UN Security Council could refer the situation to the International Criminal Court requires a unanimous vote — and both Russia and China have used their veto power to prevent such referral.

Syria is not a member of the ICC, meaning the court has no automatic jurisdiction. Without a Security Council referral, the ICC cannot act. This has created a near-complete accountability gap at the international level.

OPCW Responses

The OPCW itself took an unprecedented step: following a vote by member states in 2018, it gained the power not just to investigate chemical attacks but to attribute responsibility — something it had not previously been permitted to do. The newly created Investigation and Identification Team (IIT) has since issued several reports attributing specific attacks to Syrian government forces.

Russia has strongly contested these findings and has attempted — unsuccessfully — to strip the IIT of its mandate. The controversy has highlighted tensions between the norm-setting function of international institutions and the political realities of great-power competition.

Universal Jurisdiction: An Alternative Path

In the absence of ICC proceedings, some countries have pursued accountability through the principle of universal jurisdiction — the idea that certain crimes are so grave that any state may prosecute them regardless of where they occurred or the nationality of those involved.

In 2021, a German court in Koblenz convicted Syrian intelligence officer Eyad Al-Gharib of crimes against humanity — the first criminal conviction anywhere in the world related to Syrian state atrocities. A second, higher-profile conviction followed in 2022 with the sentencing of senior intelligence officer Anwar Raslan. France, Sweden, and the Netherlands have pursued similar cases.

What This Case Tells Us

Syria illustrates a painful reality of the current international legal order: norms against chemical weapons use are near-universally agreed upon in principle, but enforcement depends on political will that powerful states can withhold. The use of chemical weapons in Syria has not gone undocumented — on the contrary, the evidentiary record is extensive. What has failed is not knowledge but consequence.

The Syrian accountability efforts — through universal jurisdiction prosecutions, the IIIM (International, Impartial and Independent Mechanism), and civil society documentation — represent important, if partial, responses. They demonstrate that even when the primary institutions of international justice are blocked, creative legal and investigative work can still hold some perpetrators to account.