A new study from Human Rights Watch is claiming a “systematic” use of chlorine gas as an offensive weapon during the final few weeks of the Aleppo offensive, determining at least eight incidents in which military helicopters dropped such canisters into residential areas.
Over the course of that fighting there were a number of allegations of chlorine gas use by both sides. Though such allegations are not unusual whenever there is heavy fighting, particularly in populated areas where incidental leaks happen in the course of fighting.
Human Rights Watch, however, said that the eight allegations they believe to have been credible suggest they were not isolated incidents but part of a coordinated policy by the military, noting hat each of the drops happened in the immediate prelude to a significant military advance into the same area.
If confirmed, the use of chlorine would be a violation of the Chemical Weapons Convention, of which Syria is a party. The use of the gas is well short of the sort of chemical weapons Syria had in its arsenal before signing the ban, but still illegal because of the danger of civilian exposure. Human Rights Watch said the attacks may have killed as many as nine people.