Iran test-fired a high-speed torpedo on Sunday, a senior U.S. defense official told Fox News on Monday.
The Hoot torpedo, which has a range of six miles, was fired in the Strait of Hormuz. It is unclear if the torpedo test was successful, according to the news network.
The test was carried out in Iranian territorial waters and did not break any international protocols, but the advances Iran is making with this powerful torpedo -- which could travel at 250 miles per hour -- has Pentagon officials worried, said Fox News.
It is not the first time Iran has tried to test this torpedo. The last time it did so was in February 2015.
The incident marks the latest in a series of provocations from Iran.
Just last week, American officials said Iran attempted to launch a cruise missile from a submarine in the Strait of Hormuz, but failed.
In March, the U.S. aircraft carrier George H.W. Bush confronted two sets of Iranian Navy fast-attack boats that had approached a U.S.-led, five-vessel flotilla as it entered the Strait.
Earlier that month, Iranian military vessels had a close encounter with a U.S. surveillance ship in the Strait of Hormuz. The incident was described by American officials as an “unsafe” and “unprofessional” maneuver by the Iranians.
Iran’s Revolutionary Guards in turn accused the United States of provoking tensions which led to the incident.
In January, a U.S. Navy ship fired warning shots at Iranian boats near the Strait of Hormuz, after five Iranian vessels approached the USS Mahan and two other American ships that were entering the strait.
In September, the Navy said that Iran had threatened two American maritime patrol aircraft flying over the Strait of Hormuz.
A week prior to that incident, a U.S. Navy patrol ship was forced to change course after a fast attack craft from Iran's Islamic Revolutionary Guard Corps came within 91 meters of it in the central Persian Gulf.