The Biden administration is crafting plans for a sustained military campaign targeting the Houthis in Yemen after 10 days of strikes failed to halt the group’s attacks on maritime commerce, stoking concern among some officials that an open-ended operation could derail the war-ravaged country’s fragile peace and pull Washington into another unpredictable Middle Eastern conflict.

The White House convened senior officials on Wednesday to discuss options for the way ahead in the administration’s evolving response to the Iranian-backed movement, which has vowed to continue attacking ships off the Arabian peninsula despite near-daily operations to destroy Houthi radars, missiles and drones. On Saturday, U.S. Central Command announced its latest strike, on an anti-ship missile that was prepared for launch.

The deepening cycle of violence is a setback to President Biden’s goal of stemming spillover hostilities triggered by Israel’s war against Hamas in the Gaza Strip. Underscoring the threat, Iran on Saturday blamed Israel for a strike on the Syrian capital, Damascus, that killed five Iranian military advisers. The Israeli military declined to comment. In Iraq, an attack on Ain al-Asad air base, which hosts Iraqi and U.S. troops, left one Iraqi soldier seriously injured, according to a Defense Department official. An Iran-linked faction there said it was responsible.

The Houthis, one powerful faction in Yemen’s long-running civil war, have framed their campaign, which has included more than 30 missile and drone attacks on commercial and naval vessels since November, as a means of pressuring Israel, bolstering their standing amid widespread regional opposition to the Jewish state. The quickly expanding U.S. response likewise risks pulling Biden into another volatile campaign in a region that has repeatedly mired down the American military, potentially undermining his attempt to refocus U.S. foreign policy on Russia and China.

Administration officials, speaking on the condition of anonymity to discuss internal deliberations, described their strategy in Yemen as an effort to erode the Houthis’ high-level military capability enough to curtail to their ability to target shipping in the Red Sea and Gulf of Aden or, at a minimum, to provide enough of a deterrent that risk-averse shipping companies will resume sending vessels through the region’s waterways.

“We are clear-eyed about who the Houthis are, and their worldview,” a senior U.S. official said of the group, which the Biden administration designated this week as a terrorist organization. “So we’re not sure that they’re going to stop immediately, but we are certainly trying to degrade and destroy their capabilities.”

Biden this week acknowledged that the strikes had so far failed to discourage Houthi leaders, who have promised to exact revenge against the United States and Britain, whose military has contributed to the strikes in Yemen.

“Are they stopping the Houthis? No,” the president told reporters. “Will they continue? Yes.”

Officials say they don’t expect that the operation will stretch on for years like previous U.S. wars in Iraq, Afghanistan or Syria. At the same time they acknowledge they can identify no end date or provide an estimate for when the Yemenis’ military capability will be adequately diminished. As part of the effort, U.S. naval forces also are working to intercept weapons shipments from Iran.

The Houthis, who made an unlikely rise from an obscure rebel movement in Yemen’s northern mountains in the 1990s to ruling large swaths of the country by 2015, previously withstood years of bombing by a military coalition led by Saudi Arabia.

“We’re not trying to defeat the Houthis. There’s no appetite for invading Yemen,” a diplomat close to the issues said. “The appetite is to degrade their ability to launch these kind of attacks going forward, and that involves hitting the infrastructure that enables these kind of attacks, and targeting their higher-level capabilities.”

The first U.S. official said the initial U.S. and British strikes had succeeded “in significantly degrading” the military assets targeted thus far, but also acknowledged they retain a significant arsenal. “That’s not to say that the Houthis don’t still have capability, but there’s a lot that they had that they don’t have now,” he said.

Western officials believe the most advanced equipment is provided by Iran, which they say has conducted a years-long smuggling operation that has allowed them to strike far beyond Yemen’s borders. The United States is hoping that the strikes, in conjunction with its interdiction campaign that last week yielded a shipment of missile warheads, will slowly starve the Houthis of advanced weapons.

They point out that more sophisticated attacks, like a large-scale one that occurred Jan. 9, have not been repeated since the U.S.-led strikes began. “Recall before the strike we had U.S. ships attacked with 20-plus UAVs and multiple missiles in a single attack,” a second American official said.

The Houthis are likely receiving targeting assistance from Iran, the first official said. He described the group’s approach to attacking ships in the Red Sea and the Gulf of Aden as “inconsistent”: sometimes they appear to have clearly identified the nationality and affiliations of the ships they want to hit; other times they have not.

Officials said that ideology, rather than economics, was a chief driver of Biden’s decision to mount the current campaign. While the attacks have so far taken a greater financial toll on Europe than the United States, which relies on Pacific trade routes more than those in the Middle East, the Houthi campaign is already beginning to reshape the global shipping map. Some firms have chosen to reroute ships around the Cape of Good Hope off southern Africa, while major oil companies including BP and Shell suspended shipments through the area.

The officials said Biden believed the United States had to act as what they described as the world’s “indispensable nation,” with a powerful military and an ability to organize diverse nations behind a single cause. Nations including Canada, Bahrain, Germany and Japan jointly issued a statement on Jan. 3 decrying the Houthi actions.

They compared Biden’s decision to confront the Houthis to his stance in support of Ukraine, where he has authorized billions of dollars in weapons donations to help Kyiv push back against Russia’s breach of its sovereignty, a major violation of global norms.

In this case, officials said, the administration is willing to employ force to defend commercial ships’ ability to safely transit international waters and, more generally, defend the freedom of navigation. They hope the signal sent by preemptive American strikes will convince shipping firms to return to business as usual.

“It’s impossible to forecast exactly what’s going to happen, and certainly not [to predict] future operations,” the first U.S. official said. “But the principle that it simply can’t be tolerated for a terrorist organization … with these advanced capabilities to essentially shut down or control shipping through a key international choke point is one that we feel very strongly about.”

Mohammed al-Basha, a Yemen expert with the Navanti Group, said the Houthis have strong incentive to press on.

“When the Houthis attacked the Abu Dhabi airport, they garnered a lot of attention. When they attacked Aramco they garnered even more attention,” he said, referring to attacks in the United Arab Emirates and on oil facilities in Saudi Arabia. “But the attention they’re getting today from the Red Sea attacks is unheard of, so they are loving this.”

The administration has tried to avoid being seen as fueling regional violence by working to build international support, including by finding partners to sign on for declarations condemning the Houthi violence and by securing passage of a U.N. Security Council resolution denouncing their actions a day before the initial U.S. strikes. This week, the administration imposed a terrorism designation on the group.

State Department spokesman Matt Miller said the nations who have joined the United States in seeking to counter the Houthi violence were all playing “different roles.”

“There are more than 40 countries that issued a statement making clear that they condemned the Houthis’ attacks. There is a coalition of more than 20 countries that we assembled … to defend against the Houthis’ attacks,” Miller said.

Some U.S. officials have voiced concerns about the U.S. military’s intervention, worried it could unravel the hard-fought diplomatic gains aimed at ending the war in Yemen or exacerbate the already dire humanitarian situation in the Arab world’s poorest country.

Some officials at the State Department and the U.S. Agency for International Development remain concerned the U.S. assault could result in the Houthis expanding their strikes against Saudi assets - in particular oil refineries - and derail efforts to forge a peace settlement to end the nine-year war in Yemen that has killed hundreds of thousands of people and caused one of the world’s worst humanitarian disasters.

There are still several steps that haven’t been taken to solidify a peace settlement between the Houthis and the Saudis, including a payment mechanism to former Houthi fighters that are now acting in local administrator roles. Measures like that become more difficult to establish amid active hostilities between U.S. and Houthi forces.

U.S. officials also are concerned that attacking the Houthis has thrust the United States into a conflict with little exit strategy and limited support from key allies. Notably, America’s most powerful Gulf partners have withheld their backing for the American operation. The prime minister of Qatar, a key U.S. ally in the Gulf, has warned that Western strikes would not halt the violence and could fuel regional instability.

“We need to address the central issue, which is Gaza, in order to get everything else defused … If we are just focusing on the symptoms and not treating the real issues, (solutions) will be temporary,” he said, according to Reuters. More than 24,000 people have been killed in Israel’s campaign in the Gaza Strip, according to Palestinian authorities.

While U.S. lawmakers have been broadly supportive of the strikes in Yemen, they said the administration has yet to outline a clear strategy or endgame, and suggested the strikes have not eliminated concerns about an escalating Middle East conflict. Sen. Ben Cardin (D-Md.), chairman of the Senate Foreign Relations Committee, told reporters following a meeting with Secretary of State Antony Blinken in recent days that the administration’s plan for addressing the threat appeared to be “evolving.”

Legislators also voiced fears the operation could become costly and prolonged. Sen. Jack Reed (D-R.I.), chairman of the Senate Armed Services Committee, noted that some of the missiles employed to date could cost $2 million apiece. “So you’ve got this issue that will be emerging of how long can we continue to fire expensive missiles,” he said in an interview.

Sen. Richard Blumenthal (D-Conn.) noted that the United States had attempted to weaken other groups in the past, such as the Taliban or al-Qaeda, even as they rearmed. “The Houthis were rebuilding even as the Saudis bombed them [for years]. So it’s sobering,” Blumenthal said.

“There’s no question,” he added, “that we should be very clear-eyed about the difficulties here.”

Ellen Francis in Beirut, Mustafa Salim in Baghdad and Louisa Loveluck in Jerusalem contributed to this report.

previous coverage

• How Houthi attacks on ships in the Red Sea threaten Israel’s economy
• UAE warns US time running out to avoid wider Middle East crisis