(CNN) It is now clear that the deadly nerve agent sarin, the same agent which the Assad regime used to kill up to 1,500 people in East Ghouta near Damascus in August 2013, was used in the chemical attack on Idlib last week. President Bashar al-Assad appears to use chemical weapons when he is in serious trouble or bogged down in a fight. The Russians must have been aware that the Syrian regime has been using chemical weapons, in particular chlorine barrel bombs dropped from helicopters. However, I do expect that last week's chemical attack was a surprise to the Russians. At the time, most knowledgeable observers , myself included, believed the stockpile to be larger, around 1,500 tons -- with 200 tons unaccounted for.

Source: CNN April 11, 2017 16:36 UTC