The U.S. Navy destroyed three boats carrying Houthi rebels in the Red Sea on Sunday after fighters attempted to board a container ship in the second attack against the vessel this weekend.

Helicopters from two destroyers, the USS Eisenhower and USS Gravely, were dispatched after the Maersk Hangzhou issued a distress call at 6:30 a.m. Sunday morning, U.S. Central Command (CENTCOM) said on X, the ship’s second request for help in 24 hours.

Four small boats arriving from Yemen had got to within 20 meters of the Danish-owned vessel and attempted to board it, according to CENTCOM, and fired on U.S. helicopters as they approached. “The U.S. Navy helicopters returned fire in self-defense, sinking three of the four small boats, and killing the crews,” it said, adding that there was “no damage to U.S. personnel or equipment.”

On Saturday, Washington said it had shot down two anti-ship ballistic missiles after the Maersk Hangzhou issued its first distress call and reported being struck by a Houthi missile.

The United Kingdom Maritime Trade Operations organization said there were no casualties in the shipping vessel’s crew.

Since November, Iranian-backed Houthi rebels have launched over 20 attacks against ships in the Red Sea and the Bab el-Mandeb Strait, a crucial shipping lane between Europe and Asia where an estimated 15 percent of global trade passes. Several shipping lines and oil major BP have suspended operations in the area as a result.

The Houthis have said the strikes are in support of Palestinians in Gaza, where Israel is carrying out large-scale bombardments with U.S. backing in response to Hamas militants’ deadly attack against civilians in early October. In response, the U.S. set up a multinational naval taskforce to protect the route, which has been joined by countries including Denmark, Greece, the Netherlands and the U.K.