A US Navy patrol boat has fired warning shots towards an Iranian naval ship after it came within 150 yards during a tense encounter in the Persian Gulf, it has emerged.
The incident happened at 3am local time today and involved the USS Thunderbolt, a Cyclone-class ship involved in an exercise with American and other vessels in the area.
A US defense official said the Iranian Revolutionary Guard ship came within 150 yards of the Thunderbolt and did not respond to radio calls, flares or warning sirens, forcing U.S. sailors to fire warning shots.
'The IRGCN boat was coming in at a high rate of speed. It did not respond to any signals, they did not respond to any bridge-to-bridge calls, they felt there was no choice except to fire the warning shots,' the defense official said.
The Iranian boat then went 'dead in the water' after the shots and the vessels all left the area.
The incident occurred at about 3am local time in the northern Persian Gulf, when the Iranian vessel began to approach the USS Thunderbolt.
After the US ship fired the warning shots, the Iranian vessel stopped, the official said, at which point the Thunderbolt continued on her way.
The episode marks the latest in a series of close encounters between US ships and Iranian naval vessels.
The U.S. Navy recorded 35 instances of what it describes as 'unsafe and/or unprofessional' interactions with Iranian forces in 2016, compared to 23 in 2015.
Of the incidents last year, the worst involved Iranian forces capturing 10 U.S. sailors and holding them overnight. It became a propaganda coup for Iran's hard-liners, as Iranian state television repeatedly aired footage of the Americans on their knees with their hands on their heads.
Iranian forces view the American presence in the Gulf as a provocation by itself. They in turn have accused the U.S. Navy of unprofessional behavior, especially in the Strait of Hormuz, the mouth of the Persian Gulf through which a third of all oil trade by sea passes.