It is hard to explain why Bashar Assad used nerve gas — probably Sarin — in the town of Khan Sheikhoun in Syria’s northern Idlib province. On the surface, at least, it would seem to be a totally counterproductive and reckless move likely to anger the Europeans, the Americans, and even his patrons the Russians. Then why would he do it?
It was a surprise, coming as it did immediately after U.S. Ambassador Nikki Haley announced that “regime change” in Syria was no longer a priority and the U.S. focus would be on ISIS. This was a major change from the Obama administration and should have reassured Assad that he could hang on as ruler of Syria. But some pundits saw the U.S. policy shift as a perverse incentive for Assad, making it possible for him to believe he could use highly lethal chemical weapons without fear of retaliation. The Sarin would thus be a test of whether the new policy was real. To some degree, the announcement by the British prime minister that the UK had no retaliatory plans despite the attack might seem to be evidence for this argument.
It is a considerable stretch, though, to think Assad would use chemical weapons to test an American policy shift, particularly because this particular shift would have helped Assad and the Alawite minority cut a final deal that preserved their domination. It is doubtful that is the explanation.
The more likely truth is that Assad was deeply afraid that the U.S. policy shift was part of a secret deal with the Russians, one that he had to head off.
In 2014, after the first documented government use of chemicals against the Syrian population, Russia and the United States struck a deal for the removal and liquidation of Assad’s Sarin and other chemical stocks. Part of the importance of the deal lay in the fact that it was negotiated directly between Russia’s foreign minister and America’s secretary of state, making Russia and the United States the high-level guarantors of Assad’s compliance. There was not much compliance, actually — UN Secretary General Ban Ki Moon said chemical stocks remained and 5 of 12 chemical plants were still operating months after the disposal was supposed to have occurred. But regardless of what they knew (and regardless of Assad’s use of chlorine gas), the deal was considered a success until Khan Sheikhoun. This first use of Sarin since the agreement poses a direct challenge to both countries, but especially to Russia.