The US and UK never properly seized control in Iraq. We were losing troops on a daily basis. Now we have withdrawn, leaving an entirely predictable power vacuum, things have got so mental that even Iran is collaborating with us, and they are currently the main external force now loosing troops in the area. Also, this new caliphate is completely surrounded by folk who really do not like them. To be honest the whole thing looks like a deliberate trap, that is probably going to be used as a drone proving ground, given the political statements about use of troops.

Most recent geopolitical shifts can be traced back to the Middle East no longer being strategically important to U.S. interests any more. In 2007 we were worried that rising oil prices would trigger a financial crisis that would severely hurt American interests; controlling mid-east oil was critically important. By 2010 the financial crisis had happened, it was clear that gas prices were not coming down, and oil production was moving back domestically. There was no longer any reason for us to be in Iraq, so Obama got us out, and as far as the U.S. is concerned the Middle East can collapse into the Dark Ages and we won't care, as long as they leave Israel alone. So far ISIS has been more anti-Palestine than anti-Israel.

for all we know the effect ISIS is having may have been predicted and even worse, allowed to play out. From a military standpoint, they are burning off manpower and munitions that would otherwise be directed towards elements we want to protect or have interests in. Until that changes, like with all those refugees recently, I doubt we would act.

Lately US foreign policy seems vindictive rather than friendly. As in, when someone does not treat the Administration how they think they deserve or do not do what it wants the Administration gets petty.