The Iraqis asked for the US to set a date for withdrawal and to obey it. So it was not Obama's fault.
This should not have been their shot to call. Weren't there a lot of Iraqis that invited us to stay home in the first place?
The main reason people join the military is not because they are patriots, or because they are brave, it is because they are hungry and needy and need a job. This is universally true, with the exception of people who are from military families who joint the military out of family tradition. In Iraq there were a lot of such men, but they were all Sunnis. The Shias were not accepted into Saddam's upper echelon.
It does not matter what you, sirs would do. The Shia cut and run and left their weapons behind because they valued their own lives over the nation of Iraq. Loyalty in Iraq was more to the sect and tribe than to the country. Iraq is an artificial country whose borders were set by the French and the British.
Needing a job is a reason to join the military, but it is the main reason for very few.
The military are kinda picky these days and not interested in ignorant or dull soldiers, dropouts usually don't pass the bar. Convicts and poorly adjusted individuals aren't needed either.
If you can become a Ranger you can become anything.
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The US can be divided into more tribes than Iraq.
Political advantage accrues to politicians who skillfully wedge the factions apart here too.
Tribalism is not a good excuse , even if they must split this does not necessarily require war.