The U.S. launched five "self-defense" airstrikes against a series of Houthi rebel positions in Yemen on Saturday.
The strikes targeted three anti-ship missile batteries, one unmanned underwater vessel (UUV) and another unmanned surface vessel (USV), U.S. Central Command (CENTCOM) announced Sunday.
"This is the first observed Houthi employment of a UUV since attacks began in Oct. 23," CENTCOM said in a statement.
"CENTCOM identified the anti-ship cruise missiles, unmanned underwater vessel, and the unmanned surface vessel in Houthi-controlled areas of Yemen and determined they presented an imminent threat to U.S. Navy ships and merchant vessels in the region. These actions will protect freedom of navigation and make international waters safer and more secure for U.S. Navy and merchant vessels," the statement continued.
IRAN DECLARES ANTARCTICA ITS PROPERTY IN DIRECT CHALLENGE TO BIDEN, GLOBAL TREATY
The U.S. has been conducting operations in the Red Sea and near Yemen for weeks as the Iran-backed Houthis continue to harass trade through the critical passage. Houthis have launched missiles and boat attacks against international shipping vessels and U.S. Navy ships since late last year.
This weekend's strikes come roughly three weeks after a U.S. Coast Guard ship deployed to the region "seized advanced conventional weapons and other lethal aid originating in Iran and bound to Houthi-controlled areas of Yemen from a vessel in the Arabian Sea."
U.S. military officials say the Sentinel-class fast-response cutter USCGC Clarence Sutphin Jr. located the ship, boarded it and found more than 200 packages of weaponry.
CLICK HERE TO GET THE FOX NEWS APP
The packages contained "medium-range ballistic missile components, explosives, unmanned underwater/surface vehicle components, military-grade communication and network equipment, anti-tank guided missile launcher assemblies, and other military components," according to CENTCOM.
Fox News' Greg Norman contributed to this report