Huthi fighters brandish weapons as they rally during an anti-Israel and anti-US rally in Yemen's Huthi-controlled capital Sanaa on January 22, 2024
Huthi fighters brandish weapons as they rally during an anti-Israel and anti-US rally in Yemen's Huthi-controlled capital Sanaa on January 22, 2024 AFP

The United States and Britain launched a second round of joint military strikes on Yemen's Houthis on Tuesday over their attacks on Red Sea shipping, as the Iran-backed rebels vowed to hit back.

The latest raids, heard by residents of the rebel-held capital Sanaa around midnight (2100 GMT), hit eight Houthi targets, a joint US-UK statement said, while the Houthis listed 18 strikes across their territory.

US and British forces carried out a first wave of strikes against the rebel group earlier this month, and the United States launched further air raids against missiles that Washington said posed imminent threats to both civilian and military vessels.

But the Houthis have vowed to continue their attacks -- just one part of a growing crisis in the Middle East linked to the Israel-Hamas war, which has raised fears of a broader war directly involving Iran.

The latest strikes were against "eight Houthi targets in Yemen in response to the Houthis' continued attacks against international and commercial shipping as well as naval vessels transiting the Red Sea", Washington and London said in a joint statement with other countries that supported the military action.

"These precision strikes are intended to disrupt and degrade the capabilities that the Houthis use to threaten global trade and the lives of innocent mariners," the statement said.

The US Central Command said in a separate statement that the targets of the strikes "included missile systems and launchers, air defence systems, radars, and deeply buried weapons storage facilities".

British Foreign Secretary David Cameron said the Houthis had carried out more than 12 attacks on shipping since the first wave of joint strikes on January 11.

"What we have done again is send the clearest possible message that we will continue to degrade their ability to carry out these attacks... (and) that we back our words and our warnings with action," he said in a statement.

The Houthis remained defiant, with military spokesman Yahya Saree promising a response.

"These attacks will not go unanswered and unpunished," he wrote on X, formerly Twitter, listing 18 strikes in Sanaa, Hodeida, Taez and Al-Bayda provinces.

A senior US military official said the strikes were carried out using a combination of precision-guided munitions from US and British aircraft, and Tomahawk cruise missiles.

There were no concerns about civilian casualties at the sites that were hit, while Houthi losses were unknown, the official told journalists.

"The targeting was very specific and... very deliberate to go after the capability that they are using to attack maritime vessels in the Red Sea, Bab al-Mandab and Gulf of Aden," the official added.

Saree did not mention any casualties in his post on X.

Yemen's official Saba news agency said strikes hit Sanaa and several other parts of the country, while Houthi TV outlet Al-Masirah said four strikes targeted the Al-Dailami military base north of the capital, which is under rebel control.

On Monday, hours before the joint operation, Houthis claimed they fired on a US military cargo ship off the coast of Yemen.

Asked about the claim, a US defence official told AFP: "We're not seeing that at all on our end and believe that statement to be untrue."

The Yemeni rebels began striking Red Sea shipping in November, saying they were hitting Israeli-linked vessels in support of Palestinians in Gaza, which has been ravaged by the Hamas-Israel war.

The Houthis have since declared US and British interests to be legitimate targets as well.

In addition to military action, Washington is seeking to put diplomatic and financial pressure on the Houthis, redesignating them as a "terrorist" organisation last week after dropping that label soon after President Joe Biden took office.

The rebels reiterated on Monday that they will "respond to any attack" on Yemen and continue to "prevent Israeli ships" from passing through the Gulf of Aden and the Red Sea until the end of the war in Gaza.

The latest round of the Israel-Hamas conflict began after an unprecedented October attack by the Palestinian militant group that resulted in the deaths of about 1,140 people in Israel, mostly civilians, according to an AFP tally based on Israeli official figures.

Israel responded with a relentless air and ground offensive that has killed at least 25,295 people, around 70 percent of them women, children and adolescents, according to the Gaza health ministry.

Those deaths have sparked widespread anger across the region and stoked violence involving Iran-backed groups in Lebanon, Iraq and Syria as well as Yemen.