WATCH: Pentagon addresses B-2 stealth bomber strikes on Houthi bunkers, death of Hamas leader Yahya Sinwar

DUBAI, United Arab Emirates — Long-range American B-2 stealth bombers have launched airstrikes targeting underground bunkers used by Yemen’s Houthi rebels, officials said.

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It wasn’t immediately clear what damage was done in the strikes early Thursday.

However, there have been no previous reports of the B-2 Spirit being used in the strikes targeting the Houthis, who have been attacking ships for months in the Red Sea corridor over the Israel-Hamas war in the Gaza Strip.

The Houthis’ al-Masirah satellite news channel reported airstrikes around Yemen’s capital, Sanaa, which the group has held since 2014. They also reported strikes around the Houthi stronghold of Saada. They offered no immediate information on damage or casualties.

United States Defense Secretary Lloyd Austin said in a statement that the B-2 bombers targeted “five hardened underground weapons storage locations in Houthi-controlled areas of Yemen.”

The strike also appeared to be an indirect warning to Iran, the Houthis’ main benefactor, which has targeted Israel with ballistic missile attacks twice over the past year. The nuclear-capable B-2, which first saw action in 1999 in the Kosovo War, is rarely used by the U.S. military in combat as each aircraft is worth some $1 billion.