In the most serious yet of a recent string of run-ins, a U.S. Navy patrol ship is reported to have fired warning shots Wednesday at an Iranian “fast-attack” vessel that approached two American crafts in the Persian Gulf. A Pentagon official said the USS Squall fired three warning shots from a .50 caliber gun after the Iranian vessel came within 200 yards of the U.S. ship—and ignored a series of warning flares. “They did feel compelled ultimately to fire three warning shots,” said Pentagon spokesman Peter Cook. “They had taken steps already to try and de-escalate this situation.” Earlier this week, the Pentagon accused Iranian vessels of harassing a U.S. warship near the Strait of Hormuz. The Squall incident came a day before Iran’s defense minister warned of increased confrontations with American ships entering Iran’s maritime region.