This post has been updated with a statement from U.S. 5th Fleet.

The crew of the guided-missile destroyer USS Mahan (DDG-72) fired three warning shots to ward off four armed attack boats coming at the ship at high speed, a defense official confirmed to USNI News on Monday.

On Sunday, Mahan was transiting the Strait of Hormuz into the Persian Gulf when the four Iranian Revolutionary Guard Corps Navy fast inshore attack craft (FIAC) came at the destroyer at a high rate of speed with their crew-served weapons manned, the official told USNI News.

After several attempts to warn off the boats with radio communications, siren and the ship’s whistle the boats came within 900 yards of the guided missile destroyer before the crew fired three warning shots from one of the ships .50 caliber guns.

After the shots were fired, the boats broke off.

Mahan was underway along with the big deck amphib USS Makin Island (LHD-8) and U.S. a fleet oiler, the official said.

A helicopter from Makin Island also deployed a smoke screen generator, a so-called “smoke float” that did not deter the IRGCN boats.

“Naval Forces Central Command assesses this interaction as unsafe and unprofessional due to the IRGCN’s vessels high-speed approach on Mahan with weapons manned and disregard for repeated warnings via radio, audible siren and ship’s whistle, which only arrested following warning shots being fired,” read a statement from U.S. 5th Fleet provided to USNI News.

The latest clash with the IRGCN follows several high-profile encounters in August and September between IRGCN patrol boats and comes almost a year after IRGCN forces detained ten U.S. sailors who strayed into Iranian waters in the Farsi Island.

The IRGCN is separate from the Iranian Navy and has been responsible for Iranian costal defense since 2007.

They report to Iran’s religious government and are given free reign to, “boldly and courageously” in the performance of its duties, a former defense official told USNI News.

The following is a Jan. 9 statement from U.S. 5th Fleet on the encounter.

Four Islamic Revolutionary Guard Corps Navy (IRGCN) fast inshore attack

craft (FIAC) approached the guided-missile destroyer USS Mahan (DDG-72) at a

high rate of speed with their weapons manned as the ship was transiting

international waters in the Strait of Hormuz on Jan. 8.

Mahan established radio communications with the IRGCN vessels and issued

multiple radio and visual warnings to remain clear. Disregarding the

warnings, the IRGCN vessels continued to directly approach Mahan at a high

rate of speed. Mahan then fired three warning shots with a crew-served 50

caliber machine gun, and the IRGCN vessels arrested their high-speed

approach.

Naval Forces Central Command assesses this interaction as unsafe and

unprofessional due to the IRGCN’s vessels high-speed approach on Mahan with

weapons manned and disregard for repeated warnings via radio, audible siren,

and ship’s whistle, which only arrested following warning shots being fired.