Iran test-fired a high-speed torpedo on Sunday, a senior U.S. defense official told Fox News, marking the latest provocative action from the Islamic Republic.
The Hoot torpedo, which has a range of six miles, was fired in the Strait of Hormuz, where much of the world’s oil passes each day.
It's unclear if the torpedo test was successful.
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.
It is not the first time Iran has tried to test this torpedo. The last time it did so was in February 2015.
This incident came on the heels of other recent provocations from Iran.
On May 3, Iran participated in a failed cruise missile test from a submarine and in April a U.S. Navy guided-missile destroyer fired a warning flare after an Iranian Revolutionary Guard vessel approached within 1,000 meters of the USS Mahan.
Iranian officials announced in April that the Islamic Republic's defense budget increased 145 percent under President Hassan Rouhani.