@izzythepush,
If the Sunni locals are assisting ISIS or tolerating their being used as a tactic to prevent air strikes, either because they support the "cause" or hope to benefit from US pressure on Maliki to allow Sunnis a bigger role in the government, then they have chosen sides in a war.
Embedding themselves in civilian populations has become a favorite tactic of insurgents around the world when the West is militarily involved.
A) Because they don't care about civilian casualties
B) Because the West does
As long as the West allows it to work it will continue to be used.
By now the people in Masul and Takrit who have resisted ISIS (Shiia) have had their heads sawed off. The Sunni's who support ISIS have thrown their lot in with them.
I feel sure that there are Sunnis in these cities who do not support ISIS, but who fear for their lives if they attempt to leave. These folks are in a terrible position. No matter what the US decided to do or not do, they are in great peril.
There is no nice clean answer to this dilemma. No military has bombs and bullets so smart that they are able to only hit ISIS combatants and Sunni civilian supporters.
Any attempt to take back these cities without air strikes, will require troops engaged in urban warfare. Many will die and so will civilians (ISIS support not-with-standing) Ground troops are not going to attack Mosul and Takrit without tanks and artillery and both are no more, and possibly less, discriminating than air strikes.
If the US conducts the air strikes, there will at least be an effort to minimize civilian casualties, if only for optics. If the US doesn't get involved, Iran, will and they will have no compunction about killing any and all Sunnis in these cities.
If Iran, rather than the US pulls Maliki's fat out of the fire, the Iraqi Sunnis will be in worse shape than they were before ISIS invaded, and Iraq will squarely assume a role as Iranian satellite.
Unless we are going to forswear any and all future involvement in the Middle East, and turn away from strategic interests and humanitarian disasters, it is better to address this conflict now rather than its aftermath later.
And we are not going to completely pull away from the region, no matter what Obama and the isolationists in this country would like.
A showdown between the Sunni states and Iran is inevitable. The US will have to take sides.
And no matter what the haters of Israel in this country would like, we are not going to abandon them.
The lessons we should be learning from these conflicts is not that we shouldn't ever get involved, but that if we do we should anticipate insurgencies and deal with them effectively.
We've learned how to overwhelm a nation's army in a very short period of time, and, so far, we've been good at that. The mistakes made relative to the Iraq War were not anticipating insurgent/terrorist activity after the heavy bombing was over, not having an effective counter-insurgency plan, and not leaving a sufficient presence to ensure the gains that were achieved at high cost. These mistakes began with one Administration and ended with another.
I doubt that there weren't people in the Pentagon and CIA who warned or wanted to warn Rumsfeld of the aftermath of the Shock & Awe stage, but his ego is so colossal he wouldn't listen to any advice that contradicted his assessments, even after the advice proved to be correct. Bush stuck with Rumsfeld far too long, despite the advice, I"m sure, he received that a change was necessary. Either this was due to a misplaced sense of loyalty or Rumsfeld knew how to appeal to him and intellectually overpowered him. Probably both.
Once Rumsfeld was gone the Surge was ordered and Patraeus devised and executed a successful counter-insurgency strategy that remained effective until we withdrew.
These lessons of Iraq have been taught, but it remains to see if we have learned them.
Now the lesson of what will occur if the president orders a full withdrawal before all the work is done and the ultimate goal achieved is being taught. Despite what Obama said in a speech at Fort Bragg on 12/14/11, we did not leave behind
"a sovereign, stable and self-reliant Iraq." If anything proves how wrong that was, it's this mess now.
Unfortunately, wars don't get fought without civilian politicians calling the most important shots, and civilian politicians never do anything without considering politics, so there's a good chance that while the military will learn the lessons of Iraq, future Administrations will not.