U.S. forces carried out airstrikes Wednesday against Houthi militant weapons storage sites in Yemen, U.S. Defense Secretary Lloyd Austin said.

The strikes, conducted by B-2 bombers, targeted weapons the Houthis have used in a yearlong campaign of attacks against ships in the Red Sea and the Gulf of Aden that have disrupted major sea shipping routes.

“This was a unique demonstration of the United States’ ability to target facilities that our adversaries seek to keep out of reach, no matter how deeply buried underground, hardened, or fortified,” Austin said.

The Iran-backed Houthis have said their campaign of using boats, missiles and drones to target vessels is being done in solidarity with the Palestinians amid the war in Gaza.

The United States and Britain have conducted multiple strikes against the Houthis to try to protect the shipping lanes, while commercial companies have rerouted many ships to use the longer and more expensive route of going around the African continent.

“The Houthis’ illegal attacks continue to disrupt the free flow of international commerce, threaten environmental catastrophe, and put innocent civilian lives and U.S. and partner forces’ lives at risk,” Austin said.