It is true that Mr. Obama's failure to follow through on his threat that Mr. Assad would face consequences for crossing a "red line" on the use of chemical weapons was a low point of his foreign policy with lasting consequences. (In fairness, the failure was not entirely his own but was abetted by Congress, an American people wary of a military intervention in the Middle East after the Iraq War and, incidentally, a series of tweets, one in all caps, from Donald Trump.) The bargain Mr. Obama struck with Russian President Vladimir Putin to remove the Assad regime's chemical weapons turns out not to have been effective in protecting the Syrian people but has instead strengthened Mr. Putin's influence in the region, influence he has used to protect his own interests regardless of the cost to Syrian civilians.