Many of the other Democratic candidates have recently explained that they support leaving some troops in Iraq in order to prevent genocide, fight terror, keep the Kurds safe, etc.
They don't get it.
First, none of these require U.S. troops. There are certainly Shiites who kill Sunnis and Sunnis who kill Shiites in Iraq, but that is not genocide. It is a civil war. And genocide won't happen for one very basic reason-- Iraq is crawling with arms. Large scale massacre of all the followers of a group in a region (this is what genocide is) becomes impractical if the people targetted are even lightly armed-- you man ovewhelm them with force, but losing a soldier at every second or third house that they clear out would not be an acceptable rate of loss.
Second, the terrorists are there to fight us. And has recently been shown by some Sunnis turning on their former al-Qaeda allies, they don't want domination by foreign invaders. Neither us nor al-Qaeda.
Third, the Kurds were plenty autonomous and self-protecing for years without out putting troops on the ground. The only real threat they might face is Turkey's army to the north, but let's be honest here-- if the Iraqi Kurds ever want independence they have to prove that they are willing to live within the rules and mores of the world they are in. And for starters that would mean cracking down on people wanting to attack over the border into Turkey. In fact, I would join many in supporting the idea that Turkish Kurds should decide their future for themselves, but they have to renounce violence as a means to get there.
The bottom line though is that none of this requires any American troops. And if we leave troops there then the folks in Iraq who want to kill Americans will continue their work unabated. And sooner or later the troops we leave will be involved in combat and take casualties.
Far better to do something different. Let's get down a book that has likely never been dusted off in the past six years. The book of diplomacy.