But when extremist groups walk away from negotiations—as happens ten per cent of the time—they often get crushed. Sri Lanka’s Tamil Tigers pioneered the suicide vest. It was the only terrorist group to assassinate two world leaders—India’s Rajiv Gandhi, in 1991, and the Sri Lankan President Ranasinghe Premadasa, in 1993. At its peak, it controlled strategic chunks of the country. But years of sporadic peace talks broke down in 2006. In 2009, the Sri Lankan military crushed the Tigers in a relentless offensive.