A US nuclear submarine collided with a merchant ship while operating in the Persian Gulf, the US Fifth Fleet said in a statement.
No one was injured when the periscope on USS Jacksonville (SSN 699), a US Navy Los Angeles-class submarine, hit the unidentified vessel on Thursday, the navy said.
According to US officials, the Jacksonville surfaced from periscope depth to check whether there was any damage inflicted on the unidentified vessel, which "continued on a consistent course and speed offering no indication of distress or acknowledgement of a collision".
A US P-3 Orion maritime patrol aircraft conducted a search of the area and spotted "no debris in the water or vessels in distress".
One of the submarine's two periscopes suffered minor damage. The incident is under investigation, the navy said.
The waters of the Persian Gulf are relatively shallow -- average depth 150 feet -- and can sometimes be a difficult environment for operating large attack submarines, especially when large numbers of surface ships are present, according to naval officers who have operated there.
In August last year, the US Navy said one of its guided missile destroyers collided with a Japanese-owned oil tanker in the Strait of Hormuz. No one was injured.