President Obama’s cryptic call to Prime Minister Putin leads one to wonder whether Russian intelligence had knowledge of some of Tamerlan’s associates here in the U.S., thus giving the FBI some place to start looking for him. It is understandable that the administration wouldn’t give us details regarding what the Russians told us in connection with the Tsarnaevs. They don’t want to expose Russian methods and practices which would give Moscow’s enemies valuable information about what the Russian government knows about them.

But clearly the Russians know more than we have been led to believe and not sharing information about Tamerlan Tsarnaev made the FBI’s job far more difficult. It is wrong to say that if Russia had been more forthcoming about Tamerlan’s trip, the attack could have been prevented. That’s impossible to say.

But Moscow’s reluctance to clue the U.S. in on Tamerlan’s radicalization — if, as seems likely, they knew about it — made the bombers’ job easier and the FBI’s harder.