Ballistics missiles fired by Yemen’s Houthi rebels struck three commercial ships Sunday in the Red Sea, while a U.S. warship shot down three drones in self-defense during the hourslong assault, the U.S. military said. The Iranian-backed Houthis claimed two of the attacks.

The strikes marked an escalation in a series of maritime attacks in the Mideast linked to the Israel-Hamas war, as multiple vessels found themselves in the crosshairs of a single Houthi assault for the first time in the conflict. The U.S. vowed to “consider all appropriate responses” in the wake of the attack, specifically calling out Iran, after tensions have been high for years now over Tehran’s rapidly advancing nuclear program.

“These attacks represent a direct threat to international commerce and maritime security,” the U.S. military’s Central Command said in a statement. “They have jeopardized the lives of international crews representing multiple countries around the world.”

It added: “We also have every reason to believe that these attacks, while launched by the Houthis in Yemen, are fully enabled by Iran.”

The attack began around 9:15 a.m. local time (0615 GMT) in Houthi-controlled Sanaa, Yemen’s capital, Central Command said.

The USS Carney, a Navy destroyer, detected a ballistic missile fired from Houthi-controlled areas of Yemen at the Bahamas-flagged bulk carrier Unity Explorer. The missile hit near the ship, the U.S. said. Shortly afterward, the Carney shot down a drone headed its way, although it’s not clear if the destroyer was the target, Central Command said.

About 30 minutes later, the Unity Explorer was hit by a missile. While responding to its distress call, the Carney shot down another incoming drone. Central Command said the Unity Explorer sustained minor damage from the missile.

Two other commercial ships, the Panamanian-flagged bulk carriers Number 9 and Sophie II, were both struck by missiles. The Number 9 reported some damage but no casualties, and the Sophie II reported no significant damage, Central Command said.

While sailing to assist the Sophie II around 4:30 p.m. local time (1330 GMT), the Carney shot down another drone heading in its direction. The drones did no damage.

The Carney, an Arleigh Burke-class guided-missile destroyer, has shot down multiple rockets the Houthis have fired toward Israel during that nation’s war against Hamas in the Gaza Strip. It hasn’t been damaged in any of the incidents and no injuries have been reported on board. The Defense Department initially described the assault as simply an attack on the Carney before providing more details.

Houthi military spokesman Brig. Gen. Yahya Saree claimed two of Sunday’s attacks, saying the first vessel was hit by a missile and the second by a drone while in the Bab el-Mandeb Strait, which links the Red Sea to the Gulf of Aden. Saree did not mention any U.S. warship being involved.