A U.S. Navy ship fired warning shots near an armed Iranian patrol boat in the Persian Gulf on Tuesday, according to a U.S. defense official.
The official said the Iranian patrol boat came within 150 yards of the USS Thunderbolt while it was taking part in an exercise with other coalition vessels.
The Iranians didn't respond to radio calls, flares and sirens, forcing U.S. sailors to fire off warning shots. After the shots, the Iranian boat went "dead in the water."
Iran's state-run media initially didn't acknowledge the incident.
This isn't the first time the U.S. and Iran have had a tense encounter in the Persian Gulf. In 2016, the Navy said it recorded 35 instances of "unsafe and/or unprofessional" interactions with Iranian forces. That's 12 more than they recorded in 2015.
Last year, Iranian forces captured 10 U.S. soldiers and held them overnight.
The Associated Press contributed to this report.