U.S. military says it struck a Houthi underwater drone for first time

American forces hit an undersea drone during five "self-defense strikes" against Houthi rebels in areas of Yemen controlled by the Iran-backed rebels, U.S. Central Command said Sunday.

Why it matters: This is the first time U.S. forces have observed Houthis using an unmanned underwater vessel (UUV) since the group began attacking merchant and commercial ships passing through the Red Sea on Oct. 23, per a CENTCOM statement on Saturday's strikes.

Details: U.S. forces successfully struck the UUV, three mobile anti-ship cruise missiles and one unmanned surface vessel between 3-8pm Saturday Yemeni time, according to the statement.

CENTCOM had determined these five targets in Houthi-controlled areas of Yemen "presented an imminent threat to U.S. Navy ships and merchant vessels in the region," per the statement.

"These actions will protect freedom of navigation and make international waters safer and more secure for U.S. Navy and merchant vessels."