The Pentagon has said that a U.S. warship fired a warning flare after an Iranian Revolutionary Guard vessel made a close approach to the ship in the Persian Gulf.
The "unprofessional interaction" between the USS Mahan, a guided-missile destroyer, and an Iranian vessel occurred on April 25 in international waters, U.S. military officials said on April 26.
They said the Iranian vessel came within 1,000 meters of the destroyer, prompting the Mahan to send warning messages, blast a danger signal, and shoot a warning flare.
Eventually, the Iranian vessel distanced itself and steered away from Mahan, they said.
Iran's Islamic Revolutionary Guards Corp, a paramilitary force that reports directly to the Islamic republic's supreme leader, periodically sends vessels toward U.S. warships in Persian Gulf waters, ignoring U.S. radio messages and not declaring their intentions.
In January, the USS Mahan fired warning shots at an Iranian ship in the Strait of Hormuz, a vital passageway into the gulf.
The Pentagon said there were 35 similar incidents in 2016, up from 23 incidents in 2015, and seven incidents so far this year.