I would like to point out that President Obama is able to attempt a strategy of supporting Iraqi (and Kurdish) forces to fight ISIL in Iraq because George W. Bush destroyed a hostile Saddam regime that supported terrorism in the region and replaced it with a government willing to fight terrorists at our side.
Yes, during the Bush administration we built an Iraqi government and a military that, with our continued support, could be an ally to fight terrorists at our side out of the ruins of a state that fought us, threatened neighbors, and supported terrorism around the region.
President Obama refused to use the tool that we built to fight terrorists and instead ignored the growing threat of jihadis in Iraq that could have been confronted at far smaller levels of effort had we partnered with Iraq rather than doing a victory lap over Iraq by insisting we'd "responsibly ended" the war.
But despite the deterioratioin in Iraq's military that took place after we left in 2011, enough of Iraq's military remains to hold the line against ISIL and provide a basis for us to intervene with just air power (and hopefully special forces, contractors or CIA--and those of our allies, too--to call in the strikes and advise Iraqi and Kurdish units).
So as President Obama assures us that we won't have another Iraq War as he intervenes in Iraq, remember that the reason he has the luxury of this strategy is because George W. Bush led the effort to build an Iraqi military and government to fight jihadis.
Quite clearly, President Obama did not build that. He damned near let it be destroyed through his inattention.