Iraq has never been a coherent nation-state; arguably, it wouldn't exist if the British Empire hadn't installed the Kingdom of Iraq in 1932. Its three biggest communities—Sunni Arabs, Shi'a Arabs and Kurds¬—have proven themselves incapable of living together in peace. The country will probably never be both democratic and stable within its current borders. Splitting Iraq into its three constituent parts would be better for the people who live there. It would be better for us, too, insofar as this separation would prevent the kind of unstable anarchy that breeds both Sunni and Shia militias, including ISIS.

What the Next President Must Do About the World (November 2016)