The suggestion that any American administration had the power to influence decisively the course of a tremendous domestic-political upheaval in another great country on another side of the globe is intrinsically silly and childish. No great country has that sort of influence on the internal developments of any other one.
Kennan was responding to the myth-making -- still endemic -- that President Reagan single-handedly won the Cold War. It makes for a nice sound bite, and no one doubts the Reagan administration's significant contributions to the conflict's end, but it's an absurdly narrow understanding. Yet this cartoon version arguably holds sway in the minds of many of Washington's foreign policy adventurists -- the idea that with sufficient "will" and U.S. engagement, the U.S. can work its way.
It's a quote that's as relevant today -- discussing events in Syria -- as it was diagnosing the Cold War's end. The Obama administration is moving inexorably closer to an intervention in Syria. It is already directing arms shipments into the country and may soon recognize a government in exile and provide direct material and intelligence aid to forces fighting inside the country -- all done, we're told, so that the U.S. will be able to "shape" a post-war Syria to accommodate our interests.
There is very little political discussion about the crucial issues Daniel Byman and Renanah Miles raise here: mainly, what is the U.S. going to do (what can it realistically do) when Assad falls?
The answer appears to be: very little, especially if a violent struggle for power or sectarian score settling ensues. Which makes you wonder why the urge to run in in the first place.