The Problem of Pariah States

Jim Mattis, former Marine 4 star general and former Commander of CENTCOM, is a great source of quotes.  Last night, he spoke at the Aspen security forum, and criticized the Obama administration for not taking more action after Iran was tied to an attempt to assassinate the Saudi ambassador in Washington, DC.  And my only question is: what kind of action could the US take?  I simply do not know.

The problem is that pariah states, those that have been largely excluded from the international system due to their own behavior (North Korea is prime exemplar), already face the full array of sanctions, more or less.  So, how do we punish Iran when we are already punishing Iran for its nuclear programs?  Perhaps there are a few token tools left in the box, but given that we do not want war in Iran (especially if you buy Mattis's discussion of having end/exit strategies and McMaster's sharp comments about the importance of politics in wars).

Mattis argues also that Assad would have lost by now without Iranian support.  Maybe so, but we really cannot go back in the past and renegotiate the departure in Iraq to make sure Iran does not fly over the country. Iran could engage in such behavior because the US has limited tools to impose costs, and most of those tools are focused on something else--Iran's nuclear program. 

So, my point here again is this: I simply do not know what the US could have done in the assassination case that would have mattered that much. Anyone have any ideas?