A ballistic missile fired from rebel-held territory in Yemen has hit a Liberian-flagged cargo ship in the Red Sea, setting the vessel ablaze.
A US defence official said the strike happened near the Bab el-Mandeb Strait on Friday.
They identified the vessel as the MSC Palatium III and said it remained unclear whether anyone was hurt in the attack.
The missile was apparently targeting the Al Jasrah, another cargo ship that was struck by a projectile earlier in the day.
MSC, the vessel's operator, did not immediately respond to a request for comment by the Associated Press.
The incidents further escalate a campaign by Yemen's Iranian-backed Houthi rebels, who have claimed responsibility for a series of red missile assaults in recent days that just missed shipping in the Red Sea and its strategic Bab el-Mandeb Strait.
The attacks are a response to the Israel-Hamas war and the pounding air-and-ground offensive targeting the Gaza Strip, though the links to the ships targeted in the rebel assaults has grown more tenuous - or nonexistent - as the attacks continue.
Houthi rebels in Yemen did not immediately acknowledge Friday's attack.
Private intelligence firm Ambrey confirmed the earlier attack on the Al Jasrah.
"The projectile reportedly hit the port side of the vessel and one container fell overboard due to the impact," Ambrey said.
The projectile reportedly caused a fire on deck.
The British military's United Kingdom Maritime Trade Operations (UKMTO), which monitors Middle East shipping lanes, also acknowledged the first attack, warning vessels to exercise caution.
The UKMTO said there had been no reported casualties from the attack on the Al Jasrah.
The Al Jasrah is operated by German-based shipper Hapag-Lloyd, which said no crew member had been hurt in the attack.
"Hapag-Lloyd will take additional measures to secure the safety of our crews," the company said, without elaborating.
It was not clear if the attack involved a drone or a red missile.
Ambrey noted that Hapag-Lloyd "is known to have offices in the Israeli ports of Ashdod, Haifa and Tel Aviv".
On Thursday, the Houthis fired a ballistic red missile that missed a container ship travelling through the strait.
The day before that, two red missiles fired from Houthi-held territory missed a commercial tanker loaded with Indian-manufactured jet fuel near the key Bab el-Mandeb Strait.
Also near the strait, a red missile fired by Houthis on Monday night slammed into a Norwegian-flagged tanker in the Red Sea.
Global shipping has increasingly been targeted as the Israel-Hamas war threatens to become a wider regional conflict.
The Bab el-Mandeb Strait is only 18 miles wide at its narrowest point, limiting traffic to two channels for inbound and outbound shipments, according to the US Energy Information Administration.
Nearly 10 per cent of all oil traded at sea passes through it.
An estimated one trillion US dollars (£780 billion) in goods pass through the strait annually.
In November, Houthis seized a vehicle transport ship linked to Israel in the Red Sea off Yemen. The rebels still hold the vessel near the port city of Hodeida.
Separately, a container ship owned by an Israeli billionaire came under attack by a suspected Iranian drone in the Indian Ocean.
Also on Thursday, unknown attackers boarded the Malta-flagged bulk carrier Ruen, managed by Navigation Maritime Bulgare, in the Arabian Sea off the Yemeni island of Socotra, Ambrey and the UKMTO said.
Bulgarian media said the ship's 18-member crew hailed from Angola, Bulgaria and Myanmar.
No group immediately claimed responsibility for the assault.
On Friday, the UKMTO issued a warning to shippers, saying the security manager for the Ruen "believes the crew no longer has control of the vessel" and it is heading towards Somalia.
Somali piracy had dropped in recent years but there has been growing concern it could resume amid the wider chaos of the Houthi attacks and the political uncertainty gripping Somalia.
