This is an idea I am beginning to flirt with. Peacekeeping I think has been successful, in Kurdistan and Bosnia after the Dayton accords operations their were successful. They were able to prevent the escalation of conflict. Maybe they could work in Iraq.
The goal of this action is to keep the peace and prevent militants from arising in the area. We have seen from the battle of Mosul where tens of thousands of Iraqi troops were routed by Isis, that we cannot rely on their army to be equipped to face the struggles of today. But more importantly the Sunni Muslims of the north have to be protected from any reprisal attacks from the Shia population, as we have seen, in the 2003 invasion, when we fail to protect the Sunnis from these incidences they will be driven to rise up in arms.