WASHINGTON (AP) The U.S. military early Saturday struck another Houthi-controlled site in Yemen that it had determined was putting commercial vessels in the Red Sea at risk, two U.S. officials said.

Associated Press journalists in Sanaa, Yemens capital, heard one loud explosion.

The first day of strikes Friday hit 28 locations and struck more than 60 targets. However, the U.S. determined the additional location, a radar site, still presented a threat to maritime traffic, one official said.

The officials spoke anonymously to the AP to discuss an operation that hadnt yet been publicly announced.

President Joe Biden had warned Friday that the Houthis could face further strikes.

The latest strike came after the U.S. Navy on Friday warned American-flagged vessels to steer clear of areas around Yemen in the Red Sea and the Gulf of Aden for the next 72 hours after the U.S. and Britain launched multiple airstrikes targeting Houthi rebels.

The warning came as Yemens Houthis vowed fierce retaliation for the U.S.-led strikes , further raising the prospect of a wider conflict in a region already beset by Israels war in Gaza.

U.S. military and White House officials said they expected the Houthis to try to strike back.

The U.S.-led bombardment launched in response to a recent campaign of drone and missile attacks on commercial ships in the vital Red Sea killed at least five people and wounded six, the Houthis said. The U.S. said the strikes, in two waves, took aim at targets in 28 different locations across Houthi-controlled areas of Yemen.