After an Iranian patrol boat approached withing 150 yards of the USS Thunderbolt, the U.S. Navy ship was forced to fire warning shots. The incident occurred in international waters in the Persian Gulf on Tuesday, U.S. defense officials said. This most recent provocation is just the latest in a long line of Iranian aggression.

[Scroll Down for Video]

The USS Thunderbolt fired its .50-caliber machine gun near the patrol boat after the Iranians ignored repeated radio calls from the U.S. ship. Before the machine gun fire, defense officials say the boat fired warning flares.

A formation of U.S. Navy warships is doing exercises in the Northern Persian Gulf, a move that the Iranians consider to be provocative. Under these circumstances, Iran is prone to more aggressive behaviors.

Their fleet of patrol craft is comprised of fast moving speedboats. Most are equipped with a single machine-gun, though some have rocket launchers, too.

The pattern of harassment is hardly new. The most incident was in January of this year. Not four months before that, there was another. “The USS Firebolt, a patrol craft, was operating in international waters in the central Arabian Gulf, was approached by seven fast-attack craft from Iran,” Capt. Jeff Davis, a Pentagon spokesman, announced back in September of 2016.

“Three of them maneuvered close to the ship, shadowing her course from a range of about 500 yards,” he said. “They eventually broke off. One of the remaining boats turned towards the USS Firebolt and came to a stop directly in front of the ship. This caused the Firebolt to have to maneuver to avoid a collision. They came within about 100 yards of each other.”

“During the interaction, the Firebolt attempted multiple radio communications with the Iranians. This is another example of an unsafe and unprofessional interaction we’ve had with the IRGCN in the Gulf.”

“This is clearly a pattern, and it’s one we’re not happy about, and we’d like to see this sort of behavior stop.”