They describe men coughing violently, their eyes burning, their pupils shrinking.

“Soon they experience difficulty breathing, sometimes in the extreme; they begin to vomit or lose consciousness. The fighters worst affected need to be evacuated before they suffocate,” Le Monde wrote.

“Reporters from Le Monde witnessed this on several days in a row in this district, on the outskirts of Damascus, which the rebels entered in January,” it said…

“In two months spent reporting on the outskirts of the Syrian capital, we encountered similar cases across a much larger region. Their gravity, their increasing frequency and the tactic of using such arms shows that what is being released is not just tear gas, which is used on all fronts, but products of a different class that are far more toxic,” Le Monde wrote.