With its powder-soft beaches and golden-spired Buddhist temples, Thailand markets itself as a tourist haven. But the Southeast Asian nation has another side it would rather visitors not see: an Islamic insurgency in the country's far south that has claimed more than 2,100 lives since 2004. On May 31, a dozen paramilitary rangers were killed in an ambush. The following weekend, two civilians were shot dead, and 20 soccer players were injured by an on-field bomb.
Although Thailand is predominantly Buddhist, millions of Muslims live in the country's three southernmost provinces, which Thailand annexed a century ago. An insurgency has simmered...