The formal withdrawal of US troops from all the major Iraqi cities started today, which was welcomed across Iraq. But the sad part of the issue will be the absence of any control check on the terrorists and militants across Iraq in the future.
Even the fully armed US forces were unable to fully neutralize the terrorists and militants in Iraq, and the local Iraqi forces might succumb to them in no time. That could only lead to major unrest across Iraq, which might actually be fueled by the ailing and dangerous neighboring state of Iran.
Iran would prefer to tacitly support the minority Muslim groups in Iraq, for shifting the focus of the world away from Iran related issues.