Iraq right now reminds me of China in the late-Qing, early-Republican period. It is a nation that has been ravaged by foreign powers, to a point that the so-called government is incapable of inspiring leadership. Its official military force has been humiliated so often that it is riddled with corruption and completely combat ineffective.
The Shiite militia are like the warlord forces during that period. Some of them, under capable leadership, were far more effective. Yuan Shikai, for example, had a personal army that was pretty much the only combat capable army in China at the time, despite various attempts to reform the "banner armies".