I.S. = Invasive Species – NYTimes.com.

I can’t think of a better way to understand ISIS. It is a coalition. One part consists of Sunni Muslim jihadist fighters from all over the world: Chechnya, Libya, Britain, France, Australia and especially Saudi Arabia. They spread so far, so fast, despite their relatively small numbers, because the disturbed Iraqi and Syrian societies enabled these foreign jihadists to forge alliances with secular, native-born, Iraqi and Syrian Sunni tribesmen and former Baathist army officers, whose grievances were less religious and more about how Iraq and Syria were governed.

Today, ISIS — the foreigners and locals together — is putting pressure on all of Iraq’s and Syria’s native species with the avowed goal of reducing the diversity of these once polycultural societies and turning them into bleak, dark, jihadist, Sunni fundamentalist monocultures.

It is easy to see how ISIS spread. Think about the life of a 50-year-old Iraqi Sunni male from Mosul. He first got drafted to fight in the eight-year Iran-Iraq war that ended in 1988. Then he had to fight in the Persian Gulf war I after Saddam Hussein invaded Kuwait. Then he lived under a decade of U.N. sanctions that broke Iraq’s middle class. Then he had to endure the years of chaos that followed the U.S. invasion, which ended with a corrupt, brutal, pro-Iranian Shiite regime in Baghdad led by Nuri Kamal al-Maliki that did all it could to keep Sunnis poor and powerless. This was the fractured political ecosystem in which ISIS found fertile ground…