The offensive, which began in June, violates a “de-escalation” agreement that Russia negotiated with the U.S. and Jordan last summer. It has taken a devastating toll on civilians, not least because of Russian airstrikes. Meanwhile, Assad’s regime has used chemical weapons on its own people and planned to confiscate the property of those forced to flee, seemingly without perturbing Putin.

In the past, the U.S. has held the Russian government at least partially responsible for the Assad regime’s conduct. Not yesterday.

"As far as Syria is concerned," Putin said in Helsinki, "the task of establishing peace and reconciliation in this country could be the first showcase example of this successful joint work." That’s a worthwhile goal. But accomplishing it will require a change in Russian behavior.

Jessica Brandt is a fellow in the foreign policy program at the Brookings Institution.