The U.S. military carried out multiple B-2 bomber strikes on weapons storage sites in Houthi-controlled areas of Yemen, the Defense Department said Wednesday.

"U.S. forces targeted several of the Houthis' underground facilities housing various weapons components of types that the Houthis have used to target civilian and military vessels throughout the region," U.S. Defense Secretary Lloyd Austin said in a statement.

The Houthi-run Al Masirah television network reported 15 strikes at dawn Thursday local time targeting sites north and south of the capital Sanaa, as well as farther north in Saada governorate, a Houthi stronghold.

B-2 bombers conducted precision strikes against five underground weapons storage locations, Austin said, adding that the use of the long-range stealth bomber demonstrates "U.S. global strike capabilities to take action against these targets when necessary, anytime, anywhere."

The United States and Britain have repeatedly carried out strikes aimed at curbing the Houthis' ability to target shipping but the rebels have continued to attack merchant vessels transiting the Red Sea and Gulf of Aden.

"At the direction of President Biden, I authorized these targeted strikes to further degrade the Houthis' capability to continue their destabilizing behavior and to protect and defend U.S. forces and personnel in one of the world's most critical waterways," Austin said.

The Houthis, part of the "axis of resistance" of Iran-linked groups, have targeted ships they say have connections to Israel since November in support of Palestinians during Israel's genocidal war on Gaza.

The attacks have seriously disrupted a route that carries 12% of global trade, triggering the reprisal strikes by the United States and Britain that began in January.

The U.S. Central Command, which is responsible for U.S. forces in the Middle East, said on social media that there were no initial indications of civilian casualties from Wednesday's mission.

Mohammed al-Basha, a U.S.-based Yemen and Middle East security analyst, said the use of B-2 bombers indicated Washington was taking "a firmer stance" against the Houthis.

"This operation signifies a shift in U.S. policy, indicating a firmer stance against the group's destabilizing behavior as Washington intensifies efforts to degrade their military capabilities," Basha said.

The nuclear-capable B-2 first saw action in 1999 in the Kosovo War and is rarely used by the U.S. military in combat as each aircraft is worth some $1 billion.

It has dropped bombs in Afghanistan, Iraq and Libya as well. The aircraft are based at Whiteman Air Base in Missouri and typically conduct long-range strikes from there, though some B-2s were in Australia in September.