Syria’s cache of chemical weapons is believed to be the largest in the Middle East. Syrian President Bashar al-Assad’s stockpile of the nerve agent sarin stockpile “is estimated in the high hundreds of tons, possibly over 1,000 tons,” says Laicie Heeley, director of Middle East and defense policy at the Washington, D.C.-based Center for Arms Control & Non-Proliferation.

Mideast weapons proliferation expert Laicie Heeley tells Foreign Policy that most estimates for the actual sarin stockpile hover around “the high hundreds of tons, possibly over 1,000.”