Nancy A. Youssef reports: The self-proclaimed Islamic State’s loss of the Iraqi city of Tikrit this week would not have been possible without thousands of rogue Iraqi Shiite militiamen, U.S. defense officials conceded.

And that could complicate coming battles, officials said.

With the first major victory over ISIS in Iraq, those militias, many of whom are backed by neighboring Iran, will now have a greater say in how aggressively and effectively Iraq goes after the ISIS threat. They could determine which cities to attack, how much to lean on the U.S.-led coalition and when to strike. And such a varied group of fighters will likely have differing opinions from the Iraqi government, the U.S.-led coalition, Iran and even among themselves, about what needs to happen next in the battle against ISIS.

Such growing influence by such varied non-state actors will only complicate future efforts against ISIS in Iraq, defense officials and experts agreed. [Continue reading…]