The US Navy has destroyed Houthi "small boats" whose crew attempted to board a container ship in the Red Sea.
Four vessels from Houthi-controlled areas in Yemen fired upon the Maersk Hangzhou and got within metres of the ship, the US military said.
Helicopters from nearby US warships responded to a distress call - and, after being fired upon, sank three boats "in self-defence".
The crews were killed and the fourth boat fled the area.
A Houthi spokesperson said the vessel had refused to respond to warning calls, and that 10 of its group members were dead or missing after the incident.
Houthi forces have been attacking ships in the Red Sea since November, launching more than 100 drone and missile attacks on vessels passing through the vital shipping lane.
The Iranian-backed Yemeni rebel group has previously claimed its attacks are directed at vessels linked to Israel, in response to the war in Gaza.
The commercial ship targeted, the Maersk Hangzhou, is registered to Singapore and operated and owned by a Danish firm, US Central Command (Centcom) said.
The four Houthi boats attacked at around 06:30 Yemeni time (03:30 GMT) with mounted weapons and small arms, getting within 20m (66ft) of the container ship, which the crew "attempted to board". The ships crew issued a distress call and a security team returned fire, Centcom said.
Helicopters from the nearby USS Eisenhower aircraft carrier and USS Gravely destroyer responded to the call for help and were shot at while "in the process of issuing verbal calls to the small boats".
The helicopters "returned fire in self-defence, sinking three of the four small boats, and killing the crews", Centcom said. It added that the fourth boat "fled the area" and no damage had been recorded to US personnel or equipment.
It was the second attack on the Hangzhou in 24 hours, after the ship was targeted on Saturday. Centcom said anti-ship missiles were fired from Houthi-controlled areas, and the destroyers Gravely and Laboon responded.
Maersk said the attack happened at about 17:30 GMT. It confirmed that its vessel was "hit by an unknown object" but there was "no indication of fire on board".
Maersk, one of the largest shipping companies in the world, has paused sailings through the Red Sea for 48 hours.
The firm had only resumed using the route a few days ago, after the US and its allies launched a mission to protect ships in the area.
Previously, its ships had diverted on a much longer route around the Cape of Good Hope because of the recent attacks on shipping.
A US Navy admiral told the AP news agency Saturday's missile attack was the first successful strike since a global patrol was launched on 18 December.
Centcom said while the ships were responding to the distress call, two anti-ship missiles were fired from Houthi-controlled areas at the pair of US navy vessels.
The USS Gravely destroyed the inbound ballistic missiles, Centcom said, adding it was the twenty-third "illegal attack by the Houthis on international shipping" since 19 November.
Centcom added the Maersk Hangzhou was "reportedly seaworthy and there are no reported injuries" on board.
Separately, the United Kingdom Maritime Trade Operations (UKMTO) organisation reported an incident in the Red Sea about 55 nautical miles (101km) to the south-west of the Yemeni port of Hodeidah.
The organisation said an unidentified ship had reported "a loud bang accompanied by a flash on the port bow of the vessel", and several explosions.
No damage was recorded and all members of the crew were reported unhurt, with the vessel escaping the area to a nearby port, the statement said.
The rise in Houthi attacks over several weeks has led many shipping firms, including Maersk, to divert their vessels away from the Red Sea - instead travelling around the Horn of Africa.
To reach the Suez Canal in Egypt - which connects to the Mediterranean Sea - ships must pass through the tiny Bab al-Mandab Strait, just off the coast of Houthi-controlled areas in Yemen.
The Iranian-sponsored rebels have previously claimed to only target "Israel-linked" commercial ships in response to the war in Gaza, saying the attacks are an attempt to stop Israeli attacks on Palestinians.
In a statement on Sunday, UK Foreign Secretary David Cameron said he told Iran's foreign minister that Tehran "shares responsibility for preventing these attacks given their long-standing support to the Houthis".
In an interview with AP, US Navy Vice Admiral Brad Cooper said the Houthis did not seem to be ending their "reckless" attacks in light of a new maritime taskforce designed to combat them.
Earlier in December, the US launched Operation Prosperity Guardian - an international coalition to safeguard shipping in the the region.
Vice Adm Cooper added that 1,200 commercial ships had passed through the Red Sea since the operation was launched, with none hit by drone or missile strikes until Saturday.
After the international taskforce was announced, the US Department of Defense said the Houthis had carried out over 100 drone and ballistic missile attacks since November. These attempted strikes targeted 10 commercial ships linked to more than 35 different countries, it added.
The Red Sea is one of the world's most important shipping lanes as it links markets in Europe with Asia.
Analysts have warned the attacks could see a rise in prices, as it is also one of the most important routes for oil and liquefied natural gas shipments produced in the Middle East.
