Bashar Assad almost certainly crossed a 'red line' by using sarin or some other chemical weapon against his own people, President Obama said in April. The casualty toll from the latest suspected use suggests sarin henceforth will be associated with Syria and Mr. Assad.
Sarin can be deployed as a liquid (as in the Tokyo subway) but it can also be loaded onto missiles and mortars. In warheads it can be loaded with other chemicals or precursors that can convert the sarin to a nerve gas. Sarin-filled canisters can also be fired from anti-tank guns and shoulder-mounted launchers.