What lead to a change in the Iraqi government was that Maliki refused to allow US troops to stay permanently. Word is the successor comes pre-agreed on that issue.
Meanwhile IS is the enemy in Iraq but somehow we're not supposed to notice that they are our allies in Syria. Who would have thought that they might use the same weapons we gave them in A suddenly in B?
And since they are additionally quite heavily funded mostly from Saudi Arabia, which is basically the most brutal theocratic dictatorship on the planet, not to mention our favorite client state in the region, killing IS supply lines really should just be a matter of saying the word.