In a series of bloody campaigns from 2014 to 2019, a multinational military coalition drove the Islamic State group, often known as ISIS, out of much of the Iraqi and Syrian territory that the strict militant theocracy had brutally governed. But the Pentagon and the United Nations both estimate that the group still has as many as 30,000 active insurgents in the region. Thousands more IS-aligned fighters are spread across Africa and Asia, from the...

In the end, the military campaign was called Operation Ranch Hand, but it originally went by a more appropriately hellish appellation: Operation Hades. As part of this Vietnam War effort, from 1961 to 1971, the United States sprayed over 73 million liters of chemical agents on the country to strip away the vegetation that provided cover for Vietcong troops in "enemy territory." Using a variety of defoliants, the U.S. military also intentionally t...