If the three main nations of iraq were to try to divide iraq into three seperate ethnically based independent states, which "unresolved territory issue" would be most "explosive" and possibly plunge Iraq into violent conflict?

The city of Kirkuk would be the most difficult one to resolve.

Explanation:

Kirkuk is ethnically diverse where the main four groups are Arabs, Iraqi Turkmen, Kurds, and Assyrians. It would be difficult to resolve as all four ethnic groups lay claim to the city as their own for a variety of historical and cultural reasons. The Kurds claim it as a part of Kurdistan. The Turkmen claim it to be a Turkmen city. The Arabs claim it as their own having arrived in Kirkuk in the 7th century. The Assyrians lived here even before the Arabs did.

If the three main nations of Iraq were to try to divide Iraq into three (the Kurds, the Shia and the Sunni) separate ethnically based independent states, the unresolved territory issue that would be most explosive and possibly plunge Iraq into violent conflict would be the insistence from the Kurds (who have experienced a lot of oppression, genocide and injustice, and were driven out of Kirkuk by past Iraqi regimes) that they be given back the land of Kirkuk which belongs to them. Arab settlers in Kirkuk occupy the land of the Kurds; although they agree that the land belongs to the Kurds, they believe that it would be socially and economically costly if they (Arab) are displaced from the region; any attempt to displace them could lead to violent conflict in the region which has been volatile for decades.