American forces carried out air strikes against five missiles in Yemen on Sunday -- one designed for land attack and the others for targeting ships, the US military said.

The strikes came a day after US and UK forces launched a wave of air raids against Yemen's Iran-backed Huthis -- their third round of joint military action in response to the rebels' persistent attacks on shipping.

US forces "conducted a strike in self-defense against a Huthi... land attack cruise missile," and later struck "four anti-ship cruise missiles, all of which were prepared to launch against ships in the Red Sea," Central Command (CENTCOM) said on social media.

American forces "identified the missiles in Huthi-controlled areas of Yemen and determined they presented an imminent threat to US Navy ships and merchant vessels in the region," CENTCOM added.

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

US and UK forces responded with strikes against the Huthis, who have since declared American and British interests to be legitimate targets as well.

Anger over Israel's devastating campaign in Gaza -- which began after an unprecedented Hamas attack on October 7 -- has grown across the Middle East, stoking violence involving Iran-backed groups in Lebanon, Iraq, Syria and Yemen.

On January 28, a drone slammed into a base in Jordan, killing three US soldiers and wounding more than 40 -- an attack Washington blamed on Iran-backed forces.

The US responded Friday with a series of unilateral strikes on Iran-linked targets in Syria and Iraq.

'Not the end' of US strikes

The United States will press on with its retaliation against Iran-backed groups in Iraq and Syria, White House National Security Advisor Jake Sullivan said Sunday, declining to say if he ruled out strikes against Iran itself.

The United States and Britain on Saturday struck dozens of targets in Yemen in response to repeated attacks on shipping in the Red Sea and Gulf of Aden by Iran-backed Huthi rebels.

Those strikes came the day after a separate wave of unilateral American strikes against Iran-linked targets in Iraq and Syria that were carried out in response to the killing of three US soldiers in Jordan on January 28.

"That is not the end of it. We intend to take additional strikes and additional action to continue to send a clear message that the United States will respond when our forces are attacked," Sullivan told NBC news Sunday morning.

He also told ABC that the strikes have had a "good effect" in "reducing" and "degrading" such groups' abilities to carry out further attacks.

The United States has carried out a total of 85 strikes on seven separate sites in Iraq and Syria, including on command and training centers and on weapons stocks, according to the Pentagon.

Sullivan said Sunday he was unable to confirm whether the strikes had left any civilian casualties, but said the targets were "absolutely valid."

Asked whether the United States would rule out the possibility of striking Iran directly, Sullivan told NBC, "Sitting here on television, it would not be wise for me to talk about what we're ruling in and ruling out."

"If (Iran) chose to respond directly to the United States, they would be met with a swift and forceful response from us," he told ABC.

The Iran-backed Huthis began targeting Red Sea shipping in November, saying they were hitting Israel-linked vessels in support of Palestinians in Gaza, which has been ravaged by the Israel-Hamas war.