Sanaa, Yemen - The first US strikes on Yemen since President Donald Trump took office in January killed at least 31 people, the Houthis said Sunday, as Washington warned Iran to stop backing the group.

The Houthis, who have attacked Israel and Red Sea shipping in solidarity with Palestinians throughout Israel's assault on Gaza, said children were among those killed by the intense barrage of strikes.

An AFP photographer in the capital Sanaa heard three explosions and saw plumes of smoke rising.

Attacks on Sanaa, as well as on areas in Saada, Al Bayda, and Radaa, killed 31 people and wounded 101, "most of whom were children and women," Houthi health ministry spokesperson Anis Al-Asbahi said in a statement.

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Trump, in a post on social media, vowed to "use overwhelming lethal force" and ordered Iran to "immediately" cut its support.

The Houthis warned that the strikes "will not pass without response," while Iranian Foreign Minister Abbas Araghchi condemned the deaths and said Washington had "no authority" to dictate its foreign policy.

The Houthi Ansarollah website slammed "US-British aggression" and Washington's "criminal brutality."

The US Central Command (CENTCOM), which posted images of fighters and a bomb demolishing a building compound, claiming "precision strikes" were launched to "defend American interests, deter enemies, and restore freedom of navigation."

There was no immediate comment from British authorities.

"Our Yemeni armed forces are fully prepared to confront escalation with escalation," the Houthis' political bureau said in a statement on their Al-Masirah TV station.

The Houthis, who have controlled much of Yemen for more than a decade, have launched scores of drone and missile attacks at ships passing Yemen in the Red Sea and Gulf of Aden during the Gaza assault.

Pentagon spokesperson Sean Parnell said the Houthis had "attacked US warships 174 times and commercial vessels 145 times since 2023."

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The campaign crippled the vital route, which normally carries about 12% of world shipping traffic, forcing many companies into a costly detour around southern Africa.

The Palestinian group Hamas, grateful for the Houthi support, hit out Saturday at the US strikes, branding them "a stark violation of international law and an assault on the country's sovereignty and stability."

The feminist antiwar organization CODEPINK also condemned the strikes in a statement: "Instead of confronting the root causes of this violence, US officials are escalating deadly attacks on one of the poorest and most devastated nations in the Middle East, while recklessly pushing the US toward a wider regional war with Iran."

"CODEPINK and its allies demand an immediate halt to US military intervention in Yemen and across the Middle East. We call on the government to prioritize peace and justice by immediately ending all military aid and funds to Israel and holding Israel accountable for breaking the ceasefire [in Gaza]."

The US has launched several rounds of strikes on Yemen, some with British support.

After halting their attacks when Gaza's ceasefire took effect in January, the Houthis announced on Tuesday that they would resume them until Israel lifts its blockade of aid to the shattered Palestinian territory.

Trump's statement did not reference the dispute over Israel, but focused on previous Houthi attacks on merchant shipping.

"To all Houthi terrorists, YOUR TIME IS UP, AND YOUR ATTACKS MUST STOP, STARTING TODAY. IF THEY DON'T, HELL WILL RAIN DOWN UPON YOU LIKE NOTHING YOU HAVE EVER SEEN BEFORE!" he said.

"Do NOT threaten the American People, their President... or Worldwide shipping lanes. If you do, BEWARE, because America will hold you fully accountable and, we won't be nice about it!"

Earlier this month, the US reclassified the Houthi movement as a "foreign terrorist organization," banning any US interaction with it.

US Secretary of State Marco Rubio also spoke to his Russian counterpart Sergei Lavrov. Moscow is close to Tehran, which supports the Houthis.

"Continued Houthi attacks on US military and commercial shipping vessels in the Red Sea will not be tolerated," Rubio told Lavrov on Saturday, according to the State Department.

The Houthis captured Sanaa in 2014 and were poised to take control of most of the rest of the country before a Saudi-led coalition intervened. The war devastated the already impoverished nation.

Fighting has largely been on hold since a 2022 ceasefire, but the promised peace process has stalled in the face of Houthi attacks on Israel and Israel-linked shipping.