Biden faces stark choice over increasingly bold Houthi attacks

The increasingly audacious attacks come despite weeks of U.S. airstrikes and highlight the challenges of deterring the group, which is seeking to transform itself from a marginal player among Iran-aligned forces into one of the Middle East’s most formidable militant groups.

Persistent Houthi strikes are raising new questions for the Biden administration about how to bring the attacks to a halt and prevent the continuing war in the Gaza Strip from fueling a more destabilizing regional conflict.

The U.S.-led response took another hit on Sunday when a Houthi attack crippled the U.K.-owned bulk carrier Rubymar in the Red Sea, forcing the crew to abandon ship amid fears it could sink, British digital solutions company Vanguard Tech said. Ellie Shafik, head of maritime intelligence at Vanguard Tech, said the vessel appeared unlikely to be recovered.

If the Rubymar sank, it would “most probably drive even more caution by multiple stakeholders" operating around Yemen, said Ami Daniel, chief executive of London-based maritime artificial-intelligence company Windward. “Therefore, it is likely that the drop in trades in the area will further escalate."

On Tuesday, the Houthis claimed another string of attacks, including drone strikes on American warships in the Gulf of Aden and the Arabian Sea, and launches of naval missiles at what it said was an Israeli vessel as well as targets in Southern Israel. The operations were in response to “aggression and siege [on the Palestinians] and in response to the American-British aggression against our country," Houthi military spokesman Yahya Sare’e said in a statement posted on the group’s Telegram channel.

The U.S. military said Tuesday one of its destroyers shot down a Houthi antiship cruise missile heading its way.

The U.S. and a small group of allies have carried out nearly two dozen airstrikes on Houthi targets in Yemen since mid-January in an effort to end the militant attacks on ships in the Red Sea. Houthi forces have launched scores of drones and missiles at targets over the past four months in what they say is an attempt to pressure Israel to stop its war in Gaza.

The Houthis have tried to attack at least 45 ships, and the U.S. military has shot down nearly 95 drones and missiles, according to the Pentagon. Elsewhere, Iran-backed fighters have launched more than 170 attacks in Iraq, Syria and Jordan targeting the U.S. military that have killed three American service members and injured 180 others.

Houthi attacks have put a chill on global shipping, with ongoing economic shock waves spreading across the globe. The volume of traffic from North American and European vessels transiting the Red Sea was down by 67% in the week to Feb. 17 compared with October, according to Windward. Some insurers, such as Norway’s Assuranceforeningen Skuld, have stopped covering all voyages near Yemen’s waters altogether.

While attacks on U.S. forces in Jordan, Syria and Iraq have tapered off in recent days, the Houthi attacks continue unabated. A U.S. official said the Houthis purposely targeted American military ships on Sunday using antiship ballistic missiles for the first time. On Monday, the Houthis claimed responsibility for two attacks, including one in the Gulf of Aden on the U.S.-owned bulk carrier, Sea Champion, which sustained minor damage, Vanguard said.

Ali Vaez, the Iran project director at the International Crisis Group think tank in Washington, said the Houthis are less likely to follow any direction from Tehran to curtail their attacks.

“The Iranians really cannot rein the Houthis in," he said. “We see now in Iraq that they have managed to at least put a pause on the attacks on U.S. forces—probably temporarily. That’s not the kind of influence they have over the Houthis."

William Wechsler, a former assistant secretary of defense who is now senior director of the Atlantic Council’s Middle East programs, said the Biden administration should consider an expanded military campaign, including strikes to directly target Houthi leaders.

Vaez and Kevin Donegan, a retired vice admiral who led U.S. naval forces in the Middle East as commander of Fifth Fleet from 2015 to 2017, said the most effective way to curtail the Houthi threat is to bring an end to the war in Gaza.

Israel launched the war in response to Hamas’s Oct. 7 cross-border attack from Gaza that the government said killed more than 1,200 people, most of them civilians, and led to the capture of 240 hostages, half of whom are still believed to be held in the Gaza Strip.

Israel’s response has killed more than 29,000 Palestinians, most of them women and children, according to Gaza health officials, whose figures don’t distinguish between civilians and fighters. Israel has vowed to continue the war until all hostages are freed and Hamas is eliminated as a threat. But international pressure is increasing on Israel to find a diplomatic end to the fight.

“We have to get the conflict in Gaza resolved or stopped in some way," said Donegan. “That’s the only thing that’s going to allow other things to happen. In the meantime, we can’t allow the Houthis to blow up the global supply chain."

Nadwa Al-Dawsari, a nonresident fellow at the Middle East Institute who specializes in Yemen, said an expanded U.S. military campaign would also be ineffective.

“Airstrikes are not going to neutralize the Houthi capabilities," she said. “The airstrikes are validating the Houthi narrative that they are at war with America and Israel."

Dawsari encouraged the U.S. to step up its direct military support for Yemen’s government, which has struggled to defeat the Houthis over nearly a decade of civil war.

“If we don’t deal with the Houthi problem today, it will be a bigger problem to solve in the future," she said.

Nancy Youssef contributed to this article.

Write to Dion Nissenbaum at dion.nissenbaum@wsj.com and Benoit Faucon at benoit.faucon@wsj.com