DUBAI, United Arab Emirates (AP) — A bulk carrier sank days after an attack by Yemen's Houthi rebels, who are believed to have killed one mariner on board, authorities said early Wednesday. It was the second ship sunk in the rebels' campaign targeting Red Sea shipping.

The sinking of the Tutor marks what appears to be a new escalation by the Iranian-backed Houthis in their campaign of attacks on ships in the vital maritime corridor over the Israel-Hamas war in the Gaza Strip.

The attack comes despite a monthslong U.S.-led campaign in the region that has seen the Navy face its most-intense maritime fighting since World War II, with near-daily attacks targeting commercial vessels and warship.

The Liberian-flagged, Greek-owned-and-operated Tutor sank in the Red Sea, the British military's United Kingdom Maritime Trade Operations center said in a warning to sailors in the region.

“Military authorities report maritime debris and oil sighted in the last reported location,” the UKMTO said. “The vessel is believed to have sunk.”

The Houthis late Wednesday released footage showing their attack on the Tutor, acknowledging they used two different drone boats to hit the vessel from both its side and the stern.

The U.S. military did not respond to requests for comment over the sinking.

The Tutor came under attack about a week ago by a bomb-carrying Houthi drone boat in the Red Sea. John Kirby, a White House national security spokesman, said on Monday that the attack killed “a crew member who hailed from the Philippines.” The Philippines has yet to acknowledge the death, but the man who had been aboard the Tutor has been missing for over a week in the Red Sea, which faces intense summertime heat.

The use of a boat loaded with explosives raised the specter of the attack in 2000 on the USS Cole, a suicide assault by al-Qaida when the warship was at port in the Yemeni city of Aden, killing 17 on board. The Cole is now part of a U.S. Navy operation in the Red Sea led by the aircraft carrier USS Dwight D. Eisenhower to try and halt the Houthi attacks, though the rebels continue their assaults.

The Houthis have launched more than 60 attacks targeting specific vessels and fired off other missiles and drones in their campaign that has killed a total of four sailors. They've seized one vessel and sunk two since November. A U.S.-led airstrike campaign has targeted the Houthis since January, with a series of strikes May 30, killing at least 16 people and wounding 42 others, the rebels say.

In March, the Belize-flagged Rubymar carrying fertilizer cargo sank in the Red Sea after taking on water for days following a rebel attack.