The air strikes add to escalating fears of wider conflict in the region, where violence involving Tehran-aligned groups in Yemen as well as in Lebanon, Iraq and Syria has surged since the Israel-Hamas war began in early October.
Hamas said it will hold Britain and the United States "responsible for the repercussions on regional security."
The U.S., Britain and eight other allies said the strikes aimed to "de-escalate tensions." But Iran and numerous other countries in the region and beyond condemned the Western action or voiced concern that unrest could worsen.
Turkish President Recep Tayyip Erdogan described the strikes as disproportionate and said: "It is as if they aspire to turn the Red Sea into a bloodbath."
News of the air strikes sent oil prices up 4%. Bjarne Schieldrop, chief commodities analyst at Swedish bank SEB, cited market fears that "the region is on an unpredictable escalating path."
The Houthis have carried out a number of attacks on what they deem to be Israeli-linked shipping in the key Red Sea international trade route since October 7, when Hamas' unprecedented attack on Israel sparked the war still raging in the besieged Gaza Strip.
Some 12% of global maritime trade normally passes through the Bab al-Mandeb strait, but since mid-November the amount of shipping containers has dropped by 70%, according to maritime experts.
The Houthi rebels have controlled a major part of Yemen since a civil war erupted there in 2014 and are part of a regional Iran-backed "axis of resistance" against Israel and its allies.
Friday's strikes targeted an airbase, airports and a military camp, the Houthis' Al-Masirah TV station said, with AFP correspondents and witnesses reporting they could hear heavy strikes in Hodeida and Sanaa.
The British Ministry of Defence said four RAF Typhoons hit a site in northwestern Yemen in Bani, which was used to launch attack drones, as well as an airfield in Abbs, from where cruise missiles and drones were operated over the Red Sea.
'Dire consequences'
"Our country was subjected to a massive aggressive attack by American and British" forces, said Hussein al-Ezzi, the rebels' deputy foreign minister.
According to official Houthi media, he added the two countries "will have to prepare to pay a heavy price."
U.S. President Joe Biden called the strikes a "defensive action" after the Red Sea attacks and said he "will not hesitate" to order further military action if needed.
Using fighter jets and Tomahawk missiles, 60 targets at 16 Houthis locations were hit by more than 100 precision-guided munitions, U.S. Central Command said.
Unverified images on social media, some of them purportedly of Al-Dailami airbase north of the rebel-held capital Sanaa, showed explosions lighting up the sky as loud bangs and the roar of planes sounded.
Houthis military spokesman Yahya Saree said at least five people had been killed.
Nasser Kanani, spokesman for Iran's foreign ministry, said the Western strikes "will have no result other than fueling insecurity and instability in the region," while "diverting the world's attention" from Gaza.
An AFP journalist said hundreds of people rallied in Tehran against the U.S., Britain and Israel while voicing support for Gazans and Yemenis. Protesters also marched in Yemen's Gulf neighbor, Bahrain.
Saudi Arabia's foreign ministry said Riyadh "is following with great concern the military operations" and called for "self-restraint and avoiding escalation."
The kingdom is trying to extricate itself from a nine-year war with the Houthis. Fighting has largely been on hold since a truce in early 2022.
Oman, a mediator in attempts to end Yemen's civil war, said it "has warned several times about the risk of the extension of the conflict in the region."
Iraq and Syria voiced similar concerns.
'Repeated warnings'
Further afield, China said it was "concerned about the escalation of tensions in the Red Sea" and Moscow condemned the "illegitimate" strikes.
Biden called the strikes a success and said he ordered them "against a number of targets in Yemen used by Houthis rebels to endanger freedom of navigation in one of the world's most vital waterways."
He said the rebels' "unprecedented" attacks included "the use of anti-ship ballistic missiles for the first time in history."
British Prime Minister Rishi Sunak said the Houthis' breach of international law merited a "strong signal" in response.
"People can't act like this with impunity," he said, adding the Houthis attacks were "disrupting the global economy."
U.S. Defense Secretary Lloyd Austin said the strikes "targeted sites associated with the Houthis' unmanned aerial vehicle, ballistic and cruise missile, and coastal radar and air surveillance capabilities."
The Houthis said they will not be deterred. Houthis spokesman Mohammed Abdulsalam posted on X that "there is absolutely no justification for this aggression against Yemen."
Years of air raids
As the rebels have weathered years of air raids by a Saudi-led coalition, hitting them would have little impact and would only raise their standing in the Arab world, Gerald Feierstein, a former U.S. ambassador to Yemen, said before the strikes.
"The Houthis are immune to air strikes," agreed Maged Al-Madhaji, co-founder of the Sanaa Center for Strategic Studies think-tank.
U.S. and allied forces in Iraq and Syria, where they are part of an anti-militant coalition, have also faced stepped-up attacks since the Israel-Hamas war began, with Washington responding to several by bombing the sites of pro-Iran groups.
Israel has also hit targets in Syria, and has exchanged regular fire with Lebanon's Hezbollah over its northern border.
Washington in December announced a maritime security initiative, Operation Prosperity Guardian, to protect shipping in the Red Sea.
On Tuesday, however, the Houthis launched what London called their most significant attack yet, with U.S. and British forces shooting down 18 drones and three missiles.
The intensifying attacks have caused shipping companies to divert southward around South Africa's Cape of Good Hope, affecting trade flows at a time when supply strains are putting upward pressure on inflation globally.
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