Japanese shipping operator Nippon Yusen suspended sailings through the Red Sea on Tuesday after Yemen's Houthi movement vowed to step up attacks on vessels in the region.
The Iran-allied Houthi group has threatened to expand its targets to include U.S. ships in response to American and British strikes on its sites in Yemen.
Attacks by the Houthis on ships in the area since November have impacted companies and alarmed major powers, in an escalation of Israel's more than three-month-long relentless bombardment of Gaza. The group says it is acting in solidarity with Palestinians.
As well as disrupting supply chains, there are fears that the attacks could make it more difficult for policymakers to keep global inflation in check.
British and American ships had become "legitimate targets" due to the strikes launched on Yemen last week, Nasruldeen Amer, a spokesperson for the Houthis, told Al Jazeera.
The Houthis had previously said they would attack only Israeli ships or those en route to Israel.
Underlining concerns, Nippon Yusen, also known as NYK Line, has instructed its vessels navigating near the Red Sea to wait in safe waters and is considering route changes, a company spokesperson said on Tuesday.
In the latest apparent attack, the U.S. Central Command said Houthi forces in Yemen struck the U.S.-owned and operated dry bulk ship Gibraltar Eagle with an anti-ship ballistic missile on Monday. There were no reports of injuries or significant damage.
Container vessels have been pausing or diverting from the Red Sea that leads to the Suez Canal, the fastest freight route from Asia to Europe. Many ships have been forced to take the longer route via South Africa's Cape of Good Hope instead.
Weak coalition
The U.S.-led coalition meant to safeguard commercial traffic in the Red Sea is weak because regional powerhouses Saudi Arabia, the UAE and Egypt did not take part, Yemen's vice president said on Tuesday.
"This Bab al-Mandab corridor is of interest to the whole world and to the region, so regional intervention is key," Aidarous al-Zubaidi told Reuters in an interview, referring to the narrow strait at the entrance to the Red Sea.
Zubaidi's Southern Transitional Council is part of an alliance that opposes the Houthis in Yemen.
Also speaking in Davos, Chinese Premier Li Qiang said it was important to keep global supply chains "stable and smooth."
About 12% of world shipping traffic transits the Suez Canal via the Red Sea.
Vessels supplying liquefied natural gas (LNG) from Qatar are among the many ships forced to sail around Africa via the Cape of Good Hope. That diversion can add about nine days to the normally 18-day trip from Qatar to northwest Europe.
Four tankers used for shipments of Qatari LNG have resumed course after pausing for several days, LSEG ship-tracking data showed on Tuesday.
LNG tanker Al Rekayyat has resumed sailing through the Red Sea and is heading to Qatar, the data showed, after having been stopped since Jan. 13 along its Red Sea route.
The vessels Al Ghariya, Al Huwaila and Al Nuaman, loaded with Qatari LNG, were also on the move, but had changed course to head south even though they are still signaling the Suez Canal as their destinations, the data showed.
Military strikes will not contain Houthi attacks on commercial shipping but an end to the war in Gaza will, Qatar's prime minister said in Davos.
"We need to address the central issue, which is Gaza, in order to get everything else defused," said Sheikh Mohammed Bin Abdulrahman Al Thani.