A US patrol ship fired several warning shots from a heavy machine gun at an Iranian craft that approached within 150 yards and ignored other warnings, Pentagon officials told reporters on Tuesday.

USS Thunderbolt opened fire only after it tried to warn off the Iranians over the radio, by firing flares, and blowing five short blasts from its whistle, the officials said. The warning shots were fired into the water, out of concerns of a possible collision.

USS Thunderbolt fired warning shots from .50 cal machine gun at Iran boat when came within 150 yards, also ignored radio calls and flares — Lucas Tomlinson (@LucasFoxNews) July 25, 2017

The Iranian ship had approached to within 150 yards (137 meters), but “ceased its provocative actions” after the warning shots, US officials added. The vessel stayed in the area, which was described as being in “international waters in the northern Arabian Gulf,” the Pentagon’s preferred term for the Persian Gulf.

The US Navy released a video of the incident on Tuesday afternoon.

The Thunderbolt is a Cyclone-class patrol ship, operating out of the US Fifth Fleet base in Bahrain. It has a crew of four officers and 24 sailors. US officials did not specify the size or type of the Iranian vessel, only speculated that it may have been operated by the naval branch of the Islamic Revolutionary Guard Corps (IRGC).

Later on Tuesday, the IRGC issued a statement confirming that an incident took place, but said that a US Navy ship moved towards an Iranian vessel of the 3rd Naval Division and fired two rounds in an attempt to intimidate. The IRGC condemned the “unprofessional and provocative behavior” of the US crew.

US should move bases 1,000km from Iran if it wants to pursue further sanctions – army chief https://t.co/sMAfnPjavSpic.twitter.com/JI0Wvf8r2s — RT (@RT_com) July 20, 2017

In January 2016, IRGC vessels intercepted and captured two US fast-assault boats that had strayed into Iranian waters near Farsi Island. The two crews, nine men and a woman, were briefly detained on Farsi Island. The boats and the crews were released unharmed after about 15 hours.

The boats had been on their way from Kuwait to Bahrain and experienced engine trouble, according to the US Navy. The Iranian inquiry later concluded that the boats’ trespass was “not the result of a purposeful act.”

Hostility between the US and Iran date back to the 1979 Islamic revolution, which overthrew the US-backed monarchy in Tehran.