The U.S. Coast Guard fired at an Iranian fishing dhow in the Persian Gulf after the Iranian boat pointed a machine gun at the American crew, the Navy said on Tuesday.
The incident occurred earlier in the day when a team from the Coast Guard patrol vessel Monomoy was dispatched in a smaller boat "to query the Iranian dhow" in international waters, the Navy said in a statement.
"The dhow's crew trained and prepared to fire a .50 caliber machine gun on their small boat as it approached as part of a routine maritime security operation," the Navy statement said.
"This action by the dhow's crew demonstrated hostile intent," prompting the Coast Guard crew to turn away and then fire one round "in self defense," the Navy said.
Pentagon spokesman Rear Adm. John Kirby said there was no indication whether the dhow was struck.
The Navy statement said the dhow crew did not respond when fired upon and left the scene without communicating with the Monomoy.
Earlier, the Monomoy had established communication with the dhow and determined that it was an Iranian-flagged vessel, the Navy said, adding that it subsequently refused to communicate further.
No U.S. personnel were harmed and the small boat's crew returned safely to the Monomoy, the Navy statement said.
The Coast Guard is in the gulf operating with the Navy's Fifth Fleet.