I think it's clear by now that the Obama administration is not entirely concerned with the survival of the government in Iraq. The administration requested $500 million to train and equip the rebels in Syria - the same government the Obama administration has condemned for attacking ISIS in Iraq to the applause of the Iraqi government. Both US and Saudi Arabia have warned Iran about coming to the aid of Iraq, and most recently, the purchase of Russian fighters by Iraq after US refusal for any substantial support. The US priority is the overthrow of the Assad regime - which means less pressure on ISIS and the virtual isolation of Iraq - and it seems like the assumption is that ISIS can be dealt with at some undetermined point in the future.