American troops are leaving. Lets imagine for a momen the Shi'a in Iraq get testy and decide to pull an Arab spring movement against the newly established Iraqi Democracy. Iran, in a power play decides to intervene on behalf of the Shi'a in Iraq by an invasion in an attempt to install a Pro-Iranian/Shi'a Government to replace the one currently in power and subdue the Kurds in the north. What should the US reaction be?
Iraqis ain't dumb - they know what's comin'... 73% of Iraqis: Iran Is Likely to Act Aggressively When U.S. Troops Leave October 24, 2011 - About 73 percent of Iraqis said they believe it is likely Iran will act aggressively toward their country after U.S. troops leave in December.