Persian Gulf
Persian Gulf iStock

An Iranian ship seized an American military unmanned research vessel in the Gulf but released it after a US Navy patrol boat and helicopter were deployed to the location, the Pentagon said on Tuesday, according to the AFP news agency.

The US Central Command's 5th Fleet said a support ship from Iran's Islamic Revolutionary Guard Corps Navy, the Shahid Baziar, was spotted towing the seven-meter (23-foot) Saildrone Explorer unmanned surface vessel (USV) late on Monday.

The US naval drone, equipped with an array of sensors, radars and cameras, was in international waters collecting navigation and other unspecified data, the 5th Fleet said in a statement.

When the Iranian vessel was seen towing the unmanned boat, US forces sent the USS Thunderbolt coastal patrol ship, which was operating nearby, to the scene.

An MH-60S Sea Hawk helicopter based in Bahrain also flew to the location.

Those actions "resulted in the IRGCN vessel disconnecting the towing line to the USV and departing the area approximately four hours later" without further incident, the 5th Fleet said, according to AFP.

"IRGCN's actions were flagrant, unwarranted and inconsistent with the behavior of a professional maritime force," said Vice Admiral Brad Cooper, commander of US Naval Forces Central Command, in a statement.

"US naval forces remain vigilant and will continue to fly, sail and operate anywhere international law allows while promoting rules-based international order throughout the region," he added.

The incident is the latest in a series of incidents involving US and Iranian ships in the Gulf.

In June, three vessels controlled by the IRGC buzzed two American ships at what the US military called “dangerously high speed”.

The Revolutionary Guard typically patrols the shallower waters of the Persian Gulf and its narrow mouth, the Strait of Hormuz.

One such incident in May of 2020 included a tense encounter between US and Iranian ships in the Persian Gulf.

The US military said at the time that 11 Revolutionary Guards naval vessels from the Guards navy came close to US Navy and coast guard ships in the Gulf, calling the moves “dangerous and provocative”.

Iran’s Revolutionary Guard acknowledged that the incident had taken place, but also claimed that it was American forces who sparked the incident.

In April of 2020, a spokesman for the Iranian Armed Forces said that the Islamic Republic will respond “severely” if US vessels violate its territorial waters.