U.S. and British forces have carried out at least six airstrikes on Yemen’s Hodeidah International Airport and four strikes on Kamaran Island near the port of Salif off the Red Sea, Al-Masirah TV, the main television news outlet run by Yemen’s Houthi movement, said on Monday.

The strikes on Kamaran mark the first time U.S.-led coalition forces have targeted the island since airstrikes on Houthi targets began in early February.

They follow the Iran-backed Houthis’ first successful armed maritime drone strike and other missile assaults that damaged the Tutor and Verbena cargo ships last week. Both of the vessels are abandoned and adrift – with Tutor at risk of sinking, military and security experts said.

The Houthis, who control Yemen’s capital and most populous areas, have attacked international shipping in the Red Sea since November in solidarity with Palestinians in Gaza. In that time, they have sunk one ship, seized another vessel and killed three sailors in separate attacks.

Yemen’s internationally-recognised government believes Houthi fighters in the past have used Kamaran Island and Port Salif as a site to launch their Red Sea attacks as well as hide stockpiles of missiles and drones in its salt mines, two military sources within the government told Reuters.

The 10-kilometers of water that stretch from the port of Salif to Kamaran Island are also part of the route that ships must transit through to reach their next port of call.

Military and security officials said the Liberian-flagged Tutor has been taking on water since the Houthis hit it with an armed boat drone and air missiles on Wednesday in the Red Sea. That attack damaged the Tutor’s engine room and caused severe flooding.

Rescuers from the U.S. Dwight D. Eisenhower Carrier Strike Group aircraft carrier have airlifted the Tutor’s crew to safety. One sailor remains missing.

U.S. Central Command separately said crewmembers from the Palau-flagged Verbena issued a distress call this weekend due to uncontrolled fires sparked by two Houthi missile strikes in the Gulf of Aden on Thursday.

The Cayman Islands-flagged Anna-Meta wheat carrier rescued Verbena’s crew and is transporting them to safety, CENTCOM said.

Despite reprisals from the U.S.-British coalition and other navies, the Houthis have escalated their campaign against commercial vessels in one of the world’s busiest shipping lanes.

Their missile and drone attacks have forced ship owners to reroute vessels away from the vital Suez Canal shortcut – sending costs and delays cascading through the vital ocean shipping industry that transports about 80% of international trade.