On 6 January 2008, the destroyer "Hopper", "Port Royal" and the frigate were entering the Persian Gulf through the Strait of Hormuz when five Iranian boats approached them at high speed and in a threatening manner. The U.S. ships had been in the Arabian Sea searching for a sailor who had been missing from "Hopper" for one day. The US Navy says the Iranian boats made "threatening" moves toward the U.S. vessels, coming as close as . The U.S. Navy allegedly received a radio transmission saying, "I am coming at you. You will explode in a couple of minutes." As the U.S. ships prepared to fire, the Iranians abruptly turned away, the U.S. officials said. Before leaving, the Iranians dropped white boxes into the water in front of the U.S. ships. The U.S. ships did not investigate the boxes. Officials from the two nations differed on the severity of the incident. The Iranians claimed they were conducting normal maneuvers while American officials claimed that an imminent danger to American naval vessels existed.