U.S. forces launched a "self-defense" strike Monday targeting two Houthi explosive uncrewed surface vehicles (USV), officials said.

The explosives were identified in Houthi-controlled areas of Yemen and determined to present "an imminent threat to U.S. Navy ships and merchant vessels in the region," U.S. Central Command said. 

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The strike was conducted at 3:30 p.m. local time. Authorities didn't say whether the USVs were destroyed or if there were any casualties. 

On Sunday, U.S. forces conducted two strikes against the Iran-backed Houthis, including a strike against our anti-ship cruise missiles, all of which were prepared to launch against ships in the Red Sea, Centcom said. 

U.S. and coalition forces in the region have begun to take a more aggressive posture against the Houthis, which has upended the global shipping industry in the region with its constant attacks on commercial ships. 

The group has said the attacks are in response to Israel's war with Hamas. 

In addition to the Houthis, the U.S. has launched strikes against Iran-backed groups in Iraq and Syria that have initiated dozens of attacks on U.S. troops in the region.