The growing recognition of water’s strategic relevance reflects global developments. In the last three years, the Islamic State (ISIS) captured the Tabqa, Tishrin, Mosul, and Fallujah dams on the Tigris and Euphrates Rivers. ISIS subsequently lost control of all of them, but not before using them to flood or starve downstream populations, to pressure them to surrender. [...] The importance of water in the twenty-first century – comparable to that of oil in the twentieth – can hardly be overstated.