Yemen's Houthi rebels have escalated attacks on ships passing through the Red Sea during the Israel-Hamas war, raising concerns about the impact on the flow of oil, grain and consumer goods through a major global trade artery.

Israeli-linked vessels have been targeted, but the threat to trade has grown as container ships and oil tankers flagged to countries like Norway and Liberia have been attacked or drawn missile fire while traversing the waterway between Africa and the Arabian Peninsula. About 10% of the world's trade passes through the Red Sea.

In a sign of widening impact on global trade after a series of attacks or near-misses this week, Maersk, the world’s biggest shipping company, said Friday that it's told all of its vessels due to pass through a maritime chokepoint in the southern Red Sea to “pause their journey until further notice.”

German-based shipper Hapag-Lloyd that was operating a vessel attacked Friday also said it was pausing all its container ship traffic through the Red Sea until Monday. MarineTraffic, a vessel tracking firm, showed plenty of ships still moving through the region.

Here are things to know about the recent attacks and the impact on global shipping:

WHO IS ATTACKING SHIPS IN THE RED SEA AND WHY?

The Houthis are Iranian-backed rebels who swept down from their northern stronghold in Yemen and seized the capital, Sanaa, in 2014, launching a grinding war against a Saudi-led coalition seeking to restore the government.

The Houthis have sporadically targeted ships in the region, but the attacks have increased since the start of the Israel-Hamas war.

They have used drones and anti-ship missiles to attack vessels and in one case used a helicopter to seize an Israeli-owned ship and its crew.

They have threatened to attack any vessel they believe is either going to or coming from Israel. That's now escalated to apparently any vessel given recent attacks, with the Houthis also hailing vessels by radio to try to convince them to change course closer to the territory they control.

“The numerous attacks originating from Houthi-controlled territories in Yemen threaten international navigation and maritime security, in grave contravention of international law,” the European Union foreign policy office said.

WHY IS THE RED SEA IMPORTANT?

The Red Sea has the Suez Canal at its northern end and the narrow Bab el-Mandeb Strait at the southern end leading into the Gulf of Aden. It's a busy waterway with ships traversing the Suez Canal to bring goods between Asia and Europe.

A huge amount of Europe’s energy supplies, like oil and diesel fuel, come through that waterway, said John Stawpert, senior manager of environment and trade for the International Chamber of Shipping, which represents 80% of the world’s commercial fleet.

So do food products like palm oil and grain and anything else brought over on container ships, which is most of the world’s manufactured products.

HOW ARE HOUTHI ATTACKS AFFECTING TRADE?

Copenhagen-based Maersk said recent attacks on commercial vessels in the southern Red Sea “are alarming and pose a significant threat to the safety and security of seafarers.” It noted a missile was fired at but missed one of its container ships traveling from Oman to Saudi Arabia on Thursday.

“We have instructed all Maersk vessels in the area bound to pass through the Bab al-Mandab Strait to pause their journey until further notice,” the company said in statement Friday, referring to the narrow waterway that separates Yemen from East Africa and leads north to the Red Sea.

The company says it's monitoring the security situation and is working to minimize the effect on customers.

Shipper Hapag-Lloyd, whose vessel was attacked Friday, said it was pausing its ships through the Red Sea until Monday and “will decide for the period thereafter.”

Some Israeli-linked vessels have apparently started taking the longer route around Africa and the Cape of Good Hope, said Noam Raydan, senior fellow at the Washington Institute for Near East Policy. That lengthens the trip from around 19 days to 31 days depending on vessel speed, increasing costs and adding delays, she said.

The global oil market has shrugged off the most recent attacks. Prices have fallen, and the market is more worried about weak demand in major economies.

The single biggest immediate impact of the Houthi escalation has been increased insurance costs.

Recent attacks show the increased threat to vessels in the Red Sea and represent a “significant impediment” to commercial shipping in the region, said Munro Anderson, head of operations for Vessel Protect, which assesses war risks at sea and provides insurance with backing from Lloyd’s, whose members make up the world’s largest insurance marketplace.

There is “a further degree of instability facing commercial operators within the Red Sea which is likely to continue to see heightened rates across the short to medium term,” he said.

Insurance costs have doubled for shippers moving through the Red Sea, which can add hundreds of thousands of dollars to a journey for the most expensive ships, said David Osler, insurance editor for Lloyd’s List Intelligence, which provides analysis for the global maritime industry.

For Israeli ship owners, they have gone up even more — by 250% — and some insurers won’t cover them at all, he said.

While shippers are applying a so-called war risk charge of $50 to $100 per container to customers bringing over everything from grain to oil to things you buy off Amazon, that’s a low enough fee that it should not drive up prices for consumers, he said.

Osler expects insurance costs to keep rising but said the situation would have to get a lot worse — such as the loss of several ships — to raise prices considerably and make some ship owners rethink moving through the region.

“At the moment, it’s just an inconvenience that the system can handle,” he said. “Nobody likes to be paying hundreds of thousands of dollars more, but you can live with it if you have to.”

COULD THE HOUTHIS BLOCK THE RED SEA?

Unlikely, experts say. The Houthis have no formal naval warships with which to impose a cordon, relying on harassing fire and only one helicopter-borne assault so far. Meanwhile, U.S., French and other coalition warships patrol the area, keeping the waterway open.

Still, the attacks are making the shipping industry nervous, and “it’s not being taken lightly,” said Stawpert of the shipping chamber. But “you’ll still see there’s an awful lot of trade going through the Red Sea because it’s such a crucial supply line for Europe and Asia.”

He noted that the Houthis' area of influence in the waterway also remains limited.

“I just don’t see there being a possibility of the Houthis shutting transport through the Red Sea,” he said. It is “simply not how the shipping industry works. It’s not how we respond to threats like this. We will do everything we can to mitigate any such threats and keep trade flowing.”

That’s been on display in other conflicts like the war in Ukraine, with the closure of some parts of the Black Sea, Stawpert said.

He doesn't see a threat to shipping in general or closure of Red Sea routes, but “if that were to arise as a potentiality, I think we would see a much more robust reaction from navies in the area.”

Shipping Giants Pause Red Sea Route as Houthi Attacks Intensify.

 Spiraling attacks on merchant ships by Houthi militants off the coast of Yemen have prompted widespread trade disruption with some of the world’s biggest vessel owners evaluating whether it’s safe to send crews through the Red Sea.

Two of the world’s largest container shipping lines said on Friday that they were pausing transits through the Red Sea after their vessels were attacked. Two oil tanker companies have now said they are insisting on a clause in charters that will allow them to send their ships around Africa if they deem the waters off Yemen unsafe.

The moves will increase pressure on the US and its allies to improve security along one of the world’s most important trade corridors to avoid undermining the global economic recovery. An international trade group called for more military support to end the attacks.

The US “will continue to consider options and take coordinated, multilateral action to confront these unacceptable threats and attacks in the Red Sea,” said White House National Security Council spokesman Eduardo Maia Silva.

Houthi militants have been attacking more and more merchant ships in the Red Sea — especially vessels that they claim are connected to Israel — in response to the war in Gaza.

A.P. Moller-Maersk A/S, the world’s second-largest owner of container ships, said in a statement on Friday that it has instructed its vessels heading for the southern entrance of the Red Sea to pause their voyages. Its vessel Maersk Gibraltar was attacked.

Shortly after Maersk’s announcement, Germany’s Hapag-Lloyd AG announced a halt until Monday, “then will decide for the period after.”

“Following the near-miss incident involving Maersk Gibraltar yesterday and yet another attack on a container vessel today, we have instructed all Maersk vessels in the area bound to pass through the Bab al-Mandab Strait to pause their journey until further notice,” Maersk said.

Bab al-Mandab is a narrow stretch of water that links the Indian Ocean to the Red Sea. Any ship using the Suez Canal as a shortcut between Asia and Europe must go through it it.

READ: US and Allies Working to Stop Red Sea Attacks, Official Says

Maersk said its No. 1 priority was the safety of its crews, highlighting the challenge of balancing its customers’ needs against the duty to look after the staff. Sailing the long way around Africa would add thousands of miles to trade routes, boost fuel bills and delay cargo deliveries.

Euronav NV, an owner of oil supertankers, said it was insisting that its vessels be granted an option in all charters to avoid the Red Sea. On Thursday, Maersk Tankers said the same thing after one of its vessels was attacked.

Economic Risks

While it’s unclear how long-lasting Maersk and Hapag-Lloyd’s pauses will ultimately be, such steps underscore how serious and potentially economically damaging the attacks could be. Maersk owns a fleet of over 300 ships. Hapag-Lloyd ranks eighth, according to data from Clarkson Research Services Ltd.

About 12% of global trade depends on the Suez Canal and 5% on the Panama Canal, according to Marco Forgione, director general at the Institute of Export & International Trade. Panama is disrupted by drought.

“They are fundamental to the flow of international trade,” he said. “Without them operating smoothly, the domino effect of damage and disruption to supply chains caused by ships delayed and in the wrong places will be substantial.”

READ: Houthis Claim Third Red Sea Ship Attack as Trade Risks Rise

The Houthi attacks appear to have escalated in the past several days with individual ships’ connections to Israel becoming less obvious. That suggests risks are widening for the industry at large, with insurance costs climbing. At least three container ships have been attacked or disrupted near Yemen in the past day or so.

Maersk’s decision in particular will add new urgency to a US push — in the works for weeks — to form a maritime task force that will protect ships traveling through the Red Sea from Houthi attacks. White House and Pentagon officials have said the Biden administration is working with partners to form that group, with an announcement expected any day.

The Biden administration will work to strengthen and expand the maritime force, pursue “targeted efforts” at the United Nations, review potential terrorist designations for the Houthis and work with allies, Silva said. US Defense Secretary Lloyd Austin spoke with his UK counterpart, Grant Shapps, about the attacks, which now pose “a significant international problem that must be addressed” given their scale and intensity, the Pentagon said in a statement.

Snarl Trade

More broadly, the attacks will also add pressure on the US to respond to the Houthis at source, possibly with military strikes to eliminate drones and missiles before they’re launched.

The administration has resisted taking military action against the Houthis for fear of provoking a regional war, but officials including US Deputy National Security Advisor Jon Finer have acknowledged they’re not ruling out strikes.

Disruptions in the area can snarl supply chains and world trade. Back in 2021, the grounding of the Ever Given blocked the Suez Canal for almost a week, throwing ships off schedule for months and tightening the available cargo space. That accident was estimated to have cut capacity by 20% to 30% for several weeks.

“We are deeply concerned about the highly escalated security situation in the southern Red Sea and Gulf of Aden,” Maersk said in its statement Friday. “The recent attacks on commercial vessels in the area are alarming and pose a significant threat to the safety and security of seafarers.”

Military Pressure

The International Chamber of Shipping, which represents the shipping industry, on Friday praised the actions of naval forces that had assisted vessels so far. It called for the support of the full naval security forces in the region to prevent any more attacks on shipping. It also said more ships are considering diverting away from the Red Sea.

Earlier, the Yemen-based — and Iran-backed — Houthi militants said they attacked the MSC Alanya and MSC Palatium III with naval missiles. Maersk’s vessel, Maersk Gibraltar, was the target of an attack that missed on Thursday.

The ships were targeted after refusing to respond to warnings from “Yemeni naval forces,” Houthi spokesman Yahya Saree said during a protest for Gaza.

Hapag-Lloyd also said one of its vessels, the Al Jasrah, was attacked in the Red Sea on Friday.

Maersk’s notice on Friday didn’t say what would happen next. The company deals with the world’s largest retailers.

“We are committed to best possibly ensuring the stability of our customers’ supply chains, and we are working closely with all our logistics teams and are taking steps to minimize impacts to customers,” it said.