You mentioned Foreign Policy, but intend to write about COIN. Is the paper Foreign Policy or Counter-Insurgency? Regardless, I would recommend, "Cobra II: The Inside Story of the Invasion and Occupation of Iraq", by Gordan and Trainor.

If looking specifically at Foreign Policy, an angle is potentially the early 2003 de-Baathification and disbanding the Iraq military. Arguably, these two ideas created more issues than they resolved, and you could compare/contrast them with the de-Nazification of Germany post WWII.

Best of luck

John