My friend, strategist Mark Safranski, also known as the ZenPundit, offers a masterful review of What To Do About ISIS: Constructing Strategy, Weighing Options, from nothing to full-out annihilation. It really is a must read summary of the paths the US might take, having already allowed the threat to multiply manyfold by the Obama administration's ignoring it although briefed about ISIS for a year.
Now for the Obama administration, late to wake up even a little, as Safranski puts it:
Attempting to find the strategy with no risks and no hard choices is a policy to engage primarily in ineffectual military gesticulations insufficient to actually change the status quo in Iraq and Syria ( and the eternal default strategy of domestic political consultants and career bureaucrats playing at foreign policy)....
The Obama administration faces a difficult dilemma in pondering the problem presented by ISIS. I don’t envy them but their task will grow easier and a resultant strategy more likely successful if they are willing to make ruthless choices in pursuit of bottom-line, clearly-defined American interests.