[T] this time conditions are even more conducive to the Islamic State’s rebuilding. Iraq now is more politically and socially fractured than it was then. And, as one Iraqi who participated in the Awakening Councils told me, there is now no Sunni group in Iraq that can fill the void left by the Islamic State. The conflict in Syria further complicates the situation: Even if the Islamic State is driven from populated areas in both countries, the open desert border between them will make the group hard to chase. The war against the Islamic State is unwinnable without filling the political and security vacuum that now exists in too much of Iraq. The Islamic State’s eventual retreat from Mosul will be a much-needed victory for the country. But unless the government in Baghdad enables Iraqi Sunnis to fill that void, it will once again emerge from the desert.“