HODEIDA, Yemen — The US military said on Sunday its Navy helicopters fired at Iran-backed Houthi rebel boats off Yemen that were attacking a cargo ship, with Yemeni sources reporting 10 rebels killed.

The clash in the Red Sea marked a deadly escalation since the United States set up a multinational naval task force in early December to protect the vital shipping lane against Houthi attacks.

The rebels, who say they are acting in solidarity with Palestinians in the Hamas-Israel war in Gaza, have repeatedly fired drones and missiles at passing ships in the straits through which 12 percent of global trade passes.

US Central Command said the Navy had responded to a distress call from the Maersk Hangzhou, a Singapore-flagged, Denmark-owned and operated container ship that reported coming under attack for a second time in 24 hours while transiting the Red Sea.

The vessel had earlier been targeted with two anti-ship ballistic missiles. One was shot down by the US military and the other hit the Maersk Hangzhou.

The Huthis had then fired on US helicopters, which "returned fire in self-defence", sinking three of four small boats that had come within 20 meters of the ship, according to the CENTCOM statement.

It said the crews of the three vessels were killed while a fourth boat fled the area.

“Ten Houthis were killed and two were wounded in the US strike on Houthi boats that tried to stop a vessel in the sea off Hodeida,” said a source, who asked not to be named, at Yemen’s rebel-controlled Hodeida Port.

Another port source, also requesting anonymity, said that “four survivors have arrived in Hodeida with two wounded who were taken to hospital”.

Maersk suspended the passage of its vessels through the Red Sea strait for 48 hours after the latest of about two dozen attacks by Houthis on international shipping in six weeks.

The cargo ship, en route from Singapore to Egypt’s Port Suez, had made an earlier distress call after it was struck by the Huthi missile. 

CENTCOM said that assault was the 23rd illegal attack by the Huthis on international shipping since November 19.

The vessel appeared to be undamaged and “was able to continue its transit north”, Maersk, one of the world’s largest shipping companies, said in a statement.

The cargo ship was then fired on by four Huthi rebel vessels that attempted to board the vessel, according to the shipping company.

“In light of the incident, and to allow time to investigate the details of the incident and assess the security situation further — it has been decided to delay all transits through the area for the next 48 hours,” it added.

Regional tensions have spiked since the outbreak of the Gaza war.

Israel has been pounding the besieged Palestinian territory relentlessly since the Hamas militant group launched an unprecedented attacked on October 7.

Israel’s bombardment of Gaza and a ground offensive have killed 21,672 people, mostly women and children, according to the health ministry in Gaza.

US forces in Iraq and Syria have also repeatedly come under fire from drone and rocket attacks that Washington says are being carried out by Iran-backed armed groups.

And Israel has traded regular cross-border fire with the Iran-backed Hizbollah movement in Lebanon.