The United States and a handful of its allies on Thursday carried out military strikes against more than a dozen targets in Yemen controlled by the Iranian-backed Houthi militia, U.S. officials said, in an expansion of the war in the Middle East that the Biden administration had sought to avoid for three months.
The American-led air and naval strikes came in response to more than two dozen Houthi drone and missile attacks against commercial shipping in the Red Sea since November, and after warnings to the Houthis in the past week from the Biden administration and several international allies of serious “consequences” if the salvos did not stop.
But the Houthis defied that ultimatum, vowing to continue their attacks in what they say is a protest against Israel’s military campaign in Gaza. On Tuesday, American and British warships intercepted one of the largest barrages of Houthi drone and missile strikes yet, an assault that U.S. and other Western military officials said was the last straw.
Britain joined the United States in the strikes against the Houthi targets, the U.S. officials said, as strike aircraft from bases in the region and the aircraft carrier Dwight D. Eisenhower bombed targets. A Navy submarine fired Tomahawk cruise missiles, the officials said.
The Netherlands, Australia, Canada and Bahrain also were expected to participate, providing logistics, intelligence and other support, according to U.S. officials. They spoke on condition of anonymity to discuss operational matters.
The American-led strikes on Thursday hit radars, missiles and drone launch sites, and weapons storage areas, according to a U.S. official, who said President Biden had approved the retaliatory assault.
It was unclear whether the allied strikes would deter the Houthis from continuing their attacks, which have forced some of the world’s largest shipping companies to reroute vessels away from the Red Sea, creating delays and extra costs felt around the world through higher prices for oil and other imported goods.
The Houthis — whose military capabilities were honed by more than eight years of fighting against a Saudi-led coalition — have greeted the prospect of war with the United States with open delight. On Wednesday, before the strike, Abdulmalik al-Houthi, the militia’s leader, threatened to meet an American attack with a fierce response.
“We, the Yemeni people, are not among those who are afraid of America,” he said in a televised speech. “We are comfortable with a direct confrontation with the Americans.”
Some American allies in the Middle East, including the Gulf nations of Qatar and Oman, had raised concerns that strikes against the Houthis could spiral out of control and drag the region into a deeper conflict with other Iranian proxies, such as Hezbollah in Lebanon and Tehran-backed militias in Syria and Iraq.
“We never see a military action as a resolution,” Qatar’s prime minister, Sheikh Mohammed bin Abdulrahman al-Thani, said in a news conference on Sunday, stressing that Qatar would prefer to see a diplomatic solution bring an end to Houthi attacks in the Red Sea.
Administration officials have sought to separate the Houthi attacks from the conflict in Gaza, and to cast as illegitimate Houthi claims that they are acting to support the Palestinians. The officials are emphasizing that difference so that they can try to contain a wider war even as they ramp up their specific response to the Houthi attacks.
Houthi officials say that the sole goal of their attacks is to force Israel to halt its military campaign and to allow the free flow of aid into Gaza. They claim they pose no threat to global shipping.
For the Biden administration, the decision to finally strike back at the Houthis was three months in coming. Despite the barrage of attacks from the Iranian-backed militant group in the past months, the administration had hesitated to respond militarily for a number of reasons.
Mr. Biden and his top aides have been loath to take steps that could draw the United States into a wider war in the region, which was destabilized when Hamas attacked Israel on Oct. 7, killing 1,200 people and igniting the current war, according to Israeli officials. The Israeli military response has so far killed more than 23,000 people in Gaza, according to health authorities there.
There was a fear that strikes on Yemen could escalate into a tit-for-tat between American naval vessels and the Houthis and even draw Iran further into the conflict, officials said. On Thursday, Iran’s navy seized a vessel loaded with crude oil off the coast of Oman.
Top Biden aides also had been reluctant to feed the narrative that the Yemeni militia group had become so important as to warrant U.S. military retaliation. Several administration officials said that the United States was also wary of disrupting the tenuous truce in Yemen.
The Houthis, a tribal group, have taken over much of northern Yemen since they stormed its capital in 2014, effectively winning a war against the Saudi-led coalition that spent years trying to rout them. They have built their ideology around opposition to Israel and the United States, and often draw parallels between the American-made bombs that were used to pummel Yemen and those sent to Israel and used in Gaza.
“They offer bombs to kill the Palestinian people,” Mr. al-Houthi said in his speech. “Does that not provoke us? Does that not increase our determination in our legitimate stance?”
Hundreds of thousands of people have died in airstrikes and fighting in Yemen, as well as from disease and hunger, since the conflict there began. A truce negotiated in 2022 has largely held even without a formal agreement.
Last month, the Pentagon established a multinational naval task force to protect commercial ships in the Red Sea and the Gulf of Aden. The effort, called Operation Prosperity Guardian, includes Britain, Canada, France and Bahrain — the only regional ally to join. But the effort wasn’t enough to stop the Houthi attacks.
U.S. and other Western officials said the continuing attacks by the Houthis left them little choice but to respond, and they will hold the Houthis responsible for the attacks.
“We’re going to do everything we have to do to protect shipping in the Red Sea,” the U.S. national security spokesman, John Kirby, said at a news conference on Wednesday.
President Biden authorized the strikes earlier in the week and Defense Secretary Lloyd J. Austin III gave the final go-ahead from Walter Reed hospital, where he is being treated for complications from prostate cancer surgery.
The strikes came after weeks of consulting with allies. On Wednesday, Gen. Charles Q. Brown Jr., the chairman of the Joint Chiefs of Staff, was on the phone with his British counterpart, Adm. Sir Tony Radakin, to discuss the strikes, defense officials said.
In a statement, General Brown’s office said that he “reiterated the U.S. desire to work with all nations who share an interest in upholding the principle of freedom of navigation and ensuring safe passage for global shipping.”
Vivian Nereim contributed reporting from Riyadh, Saudi Arabia.