Unlike Muammar Qaddafi’s Libya, Syria is not a "friendless pariah state." The rationale for intervention that bypasses international law (a UN resolution) is that Russia would almost certainly apply a Security Council veto to any UN-sponsored initiative in Syria. But what would the response be from the West if Russia were to wage war as it saw fit, justifying its avoidance of a veto from the US and its UN Security Council allies?
UN Security Council Resolution 2011 on Libya evolved from protecting civilians to waging war; Russia signed on to the original intent, and is understandably leery this time around.
