A US Coast Guard cutter fired two volleys of warning shots Monday as a group of 13 Iranian fast boats sped toward US Navy vessels in the Persian Gulf's Strait of Hormuz in what the Pentagon called “unsafe and unprofessional” maneuvers by the naval arm of the Islamic Revolutionary Guard Corps. Pentagon press secretary John Kirby said the Iranian vessels maneuvered at high speed toward six Navy ships that were escorting the guided missile submarine USS Georgia through the Strait. After the Coast Guard cutter Maui unleashed a second volley of warning shots, the Iranian boats backed off, Kirby said. “They were acting very aggressively,” Kirby told reporters at the Pentagon. He said they got within 150 yards of the US ships, which included the guided missile cruiser USS Monterey. A day earlier, the Monterey had intercepted an arms shipment aboard a dhow in the Arabian Sea apparently headed for Yemen, whose Houthi rebels are supported by Iran. Kirby said the Maui fired two rounds of warning shots from its .50-caliber machine gun — the first round when the Iranian boats got to within 300 yards of the US ships, and the second when they got within 150 yards. “After the second round of warning shots the 13 fast attack craft from the IRGC-N broke contact,” he said, ending the encounter.