A US Navy patrol ship changed course after a fast-attack craft from Iran's Islamic Revolution Guards Corps came within 100 yards (91 meters) of it in the central Persian Gulf on Sunday, US Defense Department officials said on Tuesday.
It was at least the fourth such incident in less than a month. US officials say they are concerned that these actions by Iran could lead to mistakes.
Years of mutual animosity eased when Washington lifted sanctions on Tehran in January after a deal to curb Iran's nuclear program. But serious differences still remain over Iran's ballistic missile program and over conflicts in Syria and Iraq, Reuters reported.
Pentagon Spokesman Captain Jeff Davis said the Iranian vessel sailed directly in front of the USS Firebolt, forcing the 174-foot (53-metre) US ship to change course.
The incident began when seven Iranian ships allegedly "harassed" the Firebolt, Davis said.
Lack of Communications
A US Defense official, speaking on condition of anonymity, said the interaction was "unsafe and unprofessional due to lack of communications and the close-range harassing maneuvering", adding that uncovered and manned weapons were seen on the Iranian vessel.
The US ship tried to communicate with the Iranian ship by radio three times but received no response, the report claimed.
The US official said there have been 31 similar interactions with Iranian ships this year, almost double the amount from the same period last year.
"We don't see this type of unsafe and unprofessional activity from any other nation," the defense official asserted.
In late August, a US Navy patrol craft fired warning shots toward an Iranian fast-attack vessel that approached two US ships.
At the time, Iran's defense minister said Iranian vessels were just doing their job.
Last week, the head of US Central Command, General Joseph Votel, said "unsafe" maneuvers in the Persian Gulf were part of the Iranian government trying to exert its influence in the region.
