The New York Times reports: When it came time to make his case for the judgment of history, President Barack Obama had a ready rebuttal to one of the most cutting critiques of his time in office.

Although friends and foes alike faulted him for not following through on his threat to retaliate when Syria gassed its own people in 2013, Mr. Obama would counter that he had actually achieved a better result through an agreement with President Bashar al-Assad to surrender all of his chemical weapons.

After last week, even former Obama aides assume that he will have to rethink that passage in his memoir. More than 80 civilians were killed in what Western analysts called a sarin attack by Syrian forces — a chilling demonstration that the agreement did not succeed. In recent days, former aides have lamented what they considered one of the worst moments of the Obama presidency and privately conceded that his legacy would suffer.

“If the Syrian government carried out the attack and the agent was sarin, then clearly the 2013 agreement didn’t succeed in its objective of eliminating Bashar’s C.W.,” or chemical weapons, said Robert Einhorn, who was the State Department special adviser for nonproliferation and arms control under Mr. Obama before the agreement. “Either he didn’t declare all his C.W. and kept some hidden in reserve, or he illegally produced some sarin after his stock was eliminated — most likely the former.”

Other former advisers to Mr. Obama questioned the wisdom of negotiating with Mr. Assad and said last week’s attack illustrated the flaws in the agreement, which was brokered by President Vladimir V. Putin of Russia as a way to prevent the United States from using force.

“For me, this tragedy underscores the dangers of trying to do deals with dictators without a comprehensive, invasive and permanent inspection regime,” said Michael McFaul, who was Mr. Obama’s ambassador to Russia. “It also shows the limits of doing deals with Putin. Surely, the Russians must have known about these C.W.”

Putting the best face on it, former Obama advisers argued that it was still better to have removed 1,300 tons of chemical weapons from Syria even if Mr. Assad cheated and kept some, or later developed more. “Imagine what Syria would look like without that deal,” said Antony J. Blinken, a former deputy secretary of state. “It would be awash in chemical weapons which would fall into the hands of ISIS, Al Nusra or other groups.”

Still, the administration knew all along that it had probably not gotten all of the chemical weapons, and tried to get Russia to help press Syria, without success. “We always knew we had not gotten everything, that the Syrians had not been fully forthcoming in their declaration,” Mr. Blinken said.

Even before last week’s chemical attack, many veterans of Mr. Obama’s team considered his handling of Syria his biggest failing and expressed regret that their administration could not stop a civil war that has left more than 400,000 dead and millions displaced. [Continue reading…]