The challenges of investigating chemical weapons attacks in Syria

The last two weeks have provided a reminder of the difficulty in formally assigning blame for chemical weapons use in Syria and important steps toward addressing that problem. On Nov. 24, Syrian rebels allegedly used chlorine gas in an attack on regime-controlled parts of Aleppo. Syrian regime and Russian media sources reported the attack, which caused multiple casualties though no deaths. The Syrian Observatory for Human Rights — a more neutral source — also reported that shells fell “in Al-Khalidiya neighborhood and Jam’iyyat Al-Zahraa neighborhood,” causing “suffocation.”

Russian government and Syrian regime officials quickly blamed opposition forces for using chemical weapons. Aside from the deep hypocrisy of the Syrian regime — the primary perpetrator of chemical weapons attacks in Syria — condemning the use of chemical weapons by its opponents, the allegations against rebel forces are complicated. On one hand, Daesh has used chemical weapons in Syria, and it is possible that other opposition forces have too.

On the other hand, many observers have a complete lack of faith in official Syrian and Russian sources. Several questions have been raised about the Russian and Syrian government reports, including by Syria analyst Charles Lister, who challenged Russian claims about a specific mortar delivering the gas. Some analysts suspected that Syrian regime and Russian forces were seeking an excuse to launch an offensive in the Idlib area, despite the truce agreed between Turkey and Russia in September.

Fundamentally, in the middle of a war in which all sides have motivations to falsely accuse their opponents, it is difficult for the international community to verify whether a chemical weapons attack occurred and especially who was responsible.

There are several reasons why attribution for chemical weapons is challenging. There are practical obstacles to investigating an attack in a war zone. Experts who might be able to verify an attack and identify the source often cannot move quickly into an unsafe area, or the government or other forces might impede them. If they are delayed in reaching an attack site, evidence might have dissipated or been destroyed. Claims made by a party to the war are always suspect.

Attacks that use sophisticated nerve agents, such as sarin, are easier to attribute, since limited actors possess such weapons; in

Syria’s case, the regime is very likely to be responsible for any such attack. Attacks using more easily accessible gases, such as chlorine, theoretically could be linked to the regime or opposition forces. Delivery mechanisms also matter. Attacks involving barrel bombs pushed out of helicopters are almost certainly perpetrated by the Syrian regime, while those using more widely available forms of delivery, such as mortars, can be more difficult to attribute.

There are tools available for conducting expert investigations, primarily through the UN and especially through the Organization for the Prohibition of Chemical Weapons (OPCW). The OPCW is responsible for helping states implement the Chemical Weapons Convention (CWC), which bans the possession and use of chemical weapons. Until recently, however, the OPCW had no authority to attribute responsibility for chemical weapons attacks.