In Syria, the interventionists have lofty ends but no one wants to use the means necessary to achieve them. So we are now giving arms to the opposition and hoping it will bring the regime to the negotiating table. But, as Huntington observed, "military forces are not primarily instruments of communication to convey signals to an enemy; they are instead instruments of coercion to compel him to alter his behavior." This reminds one of the strategy of the Johnson administration in Vietnam, use force to pressure the enemy to negotiate. But the enemy is fighting to win- not to play a negotiating game.
The chance that our current efforts in Syria will do enough to achieve even our objectives is small. Eventually, the contradictions in U.S. policy will emerge and the Obama administration will face calls from people like John McCain for further escalation.
They should resist them; and it's possible that they will.