Heraldo de Madrid - US, UK air strikes pound Yemen after weeks of Red Sea attacks

The strikes targeted an airbase, airports and a military camp, the Huthi rebels' Al-Masirah TV station said, with AFP correspondents and witnesses also reporting hearing bombardments.

"Our country was subjected to a massive aggressive attack by American and British ships, submarines and warplanes," Huthi Deputy Foreign Minister Hussein Al-Ezzi said, according to official rebel media.

"America and Britain will have to prepare to pay a heavy price and bear all the dire consequences of this blatant aggression," he added.

Unverified images on social media, some of them purportedly of Al-Dailami airbase north of Sanaa, showed explosions lighting up the sky as loud bangs and the roar of planes sounded.

US President Joe Biden called the US and British strikes a "defensive action" after the Red Sea attacks, and said he "will not hesitate" to order further military action if needed.

The strikes involved fighter jets and Tomahawk missiles, several US media outlets said. US officials did not immediately confirm the reports when contacted by AFP.

"Today, at my direction, US 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 in a statement, using an alternate spelling of Huthi.

He called the strikes a "direct response" to "unprecedented" attacks by the Huthis, "including the use of anti-ship ballistic missiles for the first time in history".

"These attacks have endangered US personnel, civilian mariners, and our partners, jeopardized trade, and threatened freedom of navigation," he said.

"I will not hesitate to direct further measures to protect our people and the free flow of international commerce as necessary."

- Saudi's 'great concern' -

The strikes were "necessary and proportionate", UK Prime Minister Rishi Sunak said in a statement.

A joint statement by the US, Britain, Australia, Bahrain, Canada, Denmark, Germany, Netherlands, New Zealand and South Korea said the "aim remains to de-escalate tensions and restore stability in the Red Sea".

"But let our message be clear: we will not hesitate to defend lives and protect the free flow of commerce in one of the world's most critical waterways in the face of continued threats," it said.

Neighbouring Saudi Arabia, which is trying to end its involvement in a nine-year war with the Huthis, urged against escalation.

"The Kingdom of Saudi Arabia is following with great concern the military operations," a foreign ministry statement said, calling for "self-restraint and avoiding escalation".

The Huthis have carried out a growing number of attacks on what they deem to be Israel-linked shipping on the key international route since the eruption of the war in Gaza after Hamas's unprecedented attack on Israel on October 7.

In his statement, Biden said that on January 9 the Huthis "launched their largest attack to date -- directly targeting American ships".

The Western strikes risk turning an already-tense situation in the Middle East into a wider conflagration pitting the United States and Israel against Iran and its regional proxies.

The Huthi rebels say they are acting in response to Israel's bombardment of Gaza, and have also launched a series of drones and missiles towards Israel.

The group has controlled a major part of Yemen since a civil war erupted there in 2014, and is part of the Iran-backed "axis of resistance" arrayed against Israel.

- 'Consequences' -

The United States and its allies had issued a series of increasingly stern warnings to the Huthis to stop the shipping attacks, although Washington has been cautious about the risks of further inflaming regional tensions.

Washington set up an international coalition in December -- dubbed Operation Prosperity Guardian -- to protect maritime traffic in the area, through which 12 percent of world trade flows.

Twelve nations led by the United States later warned the Huthis on January 3 of "consequences" unless they immediately stopped attacks on commercial vessels.

But late Tuesday the Huthis launched what London called the most significant attack yet by the Yemeni rebels, with US and British forces shooting down 18 drones and three missiles.

The final straw for the Western allies appeared to come early Thursday when the US military said the Huthis fired an anti-ship ballistic missile into a shipping lane in the Gulf of Aden.

It was the 27th attack on international shipping in the Red Sea since November 19, the US military said.

The intensifying attacks have caused shipping companies to divert around South Africa's Cape of Good Hope, sparking fears of a shock to the global economy.

The United States strengthened its military posture in the region immediately after the October 7 attacks on Israel, and warned Iran and its allies not to escalate the situation.

The Biden administration was initially cautious in its response as it is seeking to preserve a fragile peace in Yemen, where a decade of civil war and a Saudi-led coalition's military campaign have led to one of the world's worst humanitarian crises in the Arabian peninsula's poorest country.

Q.Escribano--HdM