Seven Islamic Revolutionary Guard Corps Navy (IRGCN) fast in-shore attack craft (FIAC) approached USS Firebolt (PC-10) while it was operating in international waters in the central Persian Gulf on Sept. 4, a defense official told USNI News.

Three of the FIACs maneuvered close to Firebolt, mirroring the ship's course and speed at a distance of about 500 yards for about eight minutes before leaving. Another FIAC then sped towards Firebolt and stopped directly in front of the ship, causing the Firebolt crew to maneuver to avoid a collision. The U.S. ship and Iranian FIAC came within 100 yards of one another, the defense official said.

During the incident, the Firebolt crew attempted radio communication three times to understand the Iranians' intentions, but the FIAC crews never responded. The FIACs' crew-served weapons were uncovered and manned but untrained during the encounter, the official said.

U.S. Naval Forces Central Command (NAVCENT) called the interaction unsafe and unprofessional due to the lack of communication and harassment at close range, which increases the chance of collision, the defense official said.