For those skeptical of coercing ISIS into being a country, these people need to consider the difficulty of defeating a non-state actor that is heavily armed, highly motivated, and flush with cash. For example, the U.S. quickly routed the Taliban in 2001 since its Afghan leadership and military forces behaved in a conventional nation-state manner. However, since the Taliban were never eliminated nor incorporated into the Afghan political process they were able to operate as a strong insurgency in the periphery (i.e. rural areas) where Afghan governance has been inept or nonexistent. In this case, it is best to force the Islamic State into statehood, and utilize Russian military forces in Syria to shore up their border with ISIS, while providing funding and military support to the Turks, Kurds, and Iraqis to prevent further ISIS incursions into their lands.
Forcing ISIS to be a nation-state would also significantly reduce violence within Islamic State held territories; hence reducing the refugee crisis. Reasoning from a seminal book on civil wars, The Logic of Violence in Civil War, written by Yale Professor Stathis Kalyvas, facilitates a better understanding of insurgencies. He makes the argument that indiscriminate violence against civilians decreases in areas that are under full control of an incumbent government or insurgent group. In addition, Kalyvas asserts that this violence against civilians is greatest in disputed areas, as more indiscriminate violence occurs against civilians due to an inability to collect information from civilians on whom to target. Strong-arming the Islamic State into accepting a peace treaty and recognizing its current territorial sovereignty would effectively eliminate the violence against civilians in disputed areas, thus significantly slowing down the refugee crisis. It would also force the Islamic State to invest more in governing, and less in funding a fanatical fighting force.