Sana'a, Yemen - The US and Britain launched new strikes on Yemen's Houthis Monday, saying their second round of joint military action against the Iran-backed rebels was in response to continued attacks on Red Sea shipping.

American and British forces further escalated the conflict, having carried out a first wave of strikes against the rebel group earlier this month.

But the Houthis have vowed to continue their attacks – just one part of a growing crisis in the Middle East linked to Israel's relentless assault on Gaza, which has raised tensions across the region as well as fears of a broader war directly involving Iran.

The latest US-UK 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.

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"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 defense systems, radars, and deeply buried weapons storage facilities."

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

There were no concerns about civilian casualties at the sites that were hit, while Houthi losses are unknown at this time, 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. They were not intentionally selected for casualties – they were going after weapons systems," the official added.

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

Earlier on Monday, Houthis claimed they fired on a US military cargo ship off the coast of Yemen, with their spokesman Yahya Saree saying they "led a military operation targeting the American military cargo ship Ocean Jazz in the Gulf of Aden," near the Red Sea, with missiles.

Asked about the claim, a US defense 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 Huthis have since declared American 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 Huthis, re-designating them as a "terrorist" entity last week, having dropped 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 crossing the Red Sea and Gulf of Aden until the end of the war in Gaza.