US, UK launch large-scale retaliatory strikes against Iran-backed Houthi militants in Yemen

The U.S. military has unleashed large-scale retaliatory airstrikes against multiple Houthi targets in Yemen following months of attacks by the Iranian-backed militants on commercial shipping in the Red Sea, a U.S. official said Thursday.

The official said that the strikes involved a mix of fighter jets and Tomahawk cruise missiles launched from Navy surface ships and a U.S. Navy submarine, according to two U.S. officials.

One of the officials identified the submarine as the Ohio-class ballistic missile submarine USS Florida, which was seen entering the Red Sea via the Suez Canal on Nov. 5, a move publicized by U.S. Central Command.

Another U.S. official confirmed that the United Kingdom also was using its military assets to launch airstrikes against Houthi targets.

U.S. President Joe Biden, who had been under pressure to respond, but hoping to avoid risking wider Middle East conflict, issued a statement Thursday calling the move a "defensive action" after extensive warnings.

"Today, at my direction, U.S. military forces -- together with the United Kingdom and with support from Australia, Bahrain, Canada, and the Netherlands -- successfully conducted strikes against a number of targets in Yemen used by Houthi rebels to endanger freedom of navigation in one of the world's most vital waterways," Biden said. "These strikes are in direct response to unprecedented Houthi attacks against international maritime vessels in the Red Sea -- including the use of anti-ship ballistic missiles for the first time in history. These attacks have endangered U.S. personnel, civilian mariners, and our partners, jeopardized trade, and threatened freedom of navigation."

Biden monitored developments on the strikes from the West Wing of the White House on Thursday night and was briefed by National Security Advisor Jake Sullivan and Principal Deputy National Security Advisor Jon Finer, according to an administration official.

At least five people were killed and six others were wounded in the U.S.-U.K. airstrikes, according to Houthi military spokesman Brig. Gen. Yahya Saree.

"The American and British enemy bears full responsibility for its criminal aggression against our Yemeni people, and it will not go unanswered and unpunished," Saree said in a statement Friday.

Saree described 73 strikes hitting five regions of Yemen under Houthi control. He did not elaborate on what the strikes targeted.

Saree also said the Houthis will continue to target Israeli ships and those heading toward Israel's ports passing through the Red Sea.

"This brutal aggression will not dissuade Yemen from its position of support and support for the oppression of the Palestinian people," he added.

The head of the Yemeni rebel group's supreme revolutionary committee, Mohammed Ali al-Houthi, warned in a speech Friday that the "response will be greater than the response in the previous operation."

The U.S.-led retaliatory airstrikes came after Iran-backed Houthi rebels have repeatedly used drones and missiles to target commercial ships in the Red Sea and the Gulf of Aden in recent weeks, supposedly in support of Iran-backed Palestinian militant group Hamas in its war with Israel.

On Thursday, the Pentagon disclosed that a Houthi missile had landed harmlessly in the Gulf of Aden after targeting a commercial vessel marking the 27th such attack since Nov. 19.

Last week, the U.S. and other nations released a joint statement warning that "the Houthis will bear the responsibility for the consequences should they continue to threaten lives, the global economy, or the free flow of commerce in the region's critical waterways."

But on Tuesday the Houthis ignored the warning by launching their biggest barrage yet as American and British destroyers, along with U.S. Navy jets, shot down 21 drones and missiles aimed at dozens of ships in the Red Sea.

Since then, senior U.S. officials had issued new warnings against the Houthis to stop with the attacks.

"The Houthis need to stop these attacks," John Kirby, coordinator for strategic communications at the National Security Council, told White House reporters on Thursday. "They will bear the consequences for any failure to do so."

However, Kirby said the U.S. was "not going to telegraph our punches one way or another here."

"Today's strikes targeted the Houthis' unmanned aerial vehicle, uncrewed surface vessel, land-attack cruise missile, and coastal radar and air surveillance capabilities," U.S. Defense Secretary Lloyd Austin said in a statement Thursday night, issued from the hospital where he remains after complications from cancer treatment. "The United States maintains its right to self-defense and, if necessary, we will take follow-on actions to protect U.S. forces," he said.

While Thursday's airstrikes were intended to lessen the Houthis' capability to go after ships in the Red Sea, the president will "not hesitate to direct further measures" if they continue, senior administration and senior military officials told reporters on a call Thursday night.

"This was a significant action and conducted with every objective and every expectation that will degrade in a significant way the Houthis' capability to launch exactly the sorts of attacks that they have conducted over the period of recent weeks," a senior administration official said.

"As to whether this will merely degrade or also deter -- I guess I can't do better than what the president has said, which is that he will not hesitate to direct further measures to protect our people in the free flow of international commerce as necessary," the official said.

"So this may well not be the last word on the topic. And when we have more to say and more to do, you will hear from us."

The senior officials declined to give specific details on how the large-scale attacks "degraded" the Houthis' capabilities but said generally they intended to disrupt the Houthis' missile, radar and UAV abilities.

"The capabilities that are essential to the Houthis campaign against commercial shipping in international waters," the senior administration official said.

Since the attack, the U.S. has not seen any "direct retaliatory action" from the Houthis, the senior military official said.

Earlier Thursday in London, British Prime Minister Rishi Sunak convened a meeting of his top national security officials and members of Parliament were briefed leading to speculation that retaliatory strikes in Yemen were imminent.

The United Kingdom forms part of the 20 countries that make up the U.S.-led Operation Prosperity Guardian established in late December to defend commercial vessels from Houthi attacks as they transited the Red Sea.

Sunak also released a statement on Thursday's airstrikes.

"Despite the repeated warnings from the international community, the Houthis have continued to carry out attacks in the Red Sea, including against UK and US warships just this week," Sunak said. "This cannot stand. The United Kingdom will always stand up for freedom of navigation and the free flow of trade. We have therefore taken limited, necessary and proportionate action in self-defence."

The shipping route through the Bab-el-Mandeb Strait into the Red Sea is a vital waterway through which 15% of the world's commerce transits.

The attacks had led some of the world's largest shipping companies to have their ships avoid the waterway and take the longer routes around Africa.

The Houthis have controlled parts of Yemen since 2014 and have demonstrated a willingness to expand their internal conflict beyond the country's borders.

In October 2016, Houthi radar sites were targeted by U.S. airstrikes following anti-ship missile attacks targeting a U.S. Navy destroyer sailing in international waters.

Thursday's strikes hit multiple targets, including in Yemen's capital of San'a.

"Our country was subjected to a massive aggressive attack by American and British ships, submarines, and warplanes, and America and Britain will undoubtedly have to prepare to pay a heavy price and bear all the dire consequences of this blatant aggression," Houthi Deputy Foreign Minister Hussein al-Ezzi posted on X Thursday night.

ABC News' Nasser Atta, Ahmed Baider and Justin Gomez contributed to this report.