The US and Britain have launched strikes against 36 Houthi targets in Yemen, in the second day of major US operations against Iran-aligned groups following a deadly attack on US troops last weekend.

The strikes late on Saturday hit buried weapons storage facilities, missile systems, launchers and other capabilities the Houthis have used to attack Red Sea shipping, the Pentagon said, adding it targeted 13 locations across the country.

They are the latest blows in a conflict that has spread into the Middle East since October 7 when the Palestinian militant group Hamas stormed Israel from the Gaza Strip, igniting a war that has drawn Iran-allied groups into attacks on US and Israeli targets on several fronts.

The Houthi military spokesman Yahya Sarea said the strikes “will not pass without a response and consequences”.

“The building I live in shook,” said Fatimah, a resident of Houthi-controlled Sanaa, adding that it had been years since she had felt such blasts in a country that has suffered years of war.

The Houthis did not announce any casualties.

The Yemen strikes are running parallel to an unfolding US campaign of retaliation over the killing of three US soldiers in a drone strike by Iraqi-based Iran-backed militants on an outpost in Jordan a week ago.

On Friday, the US carried out the first wave of that retaliation, striking in Iraq and Syria more than 85 targets linked to Iran’s Islamic Revolutionary Guard Corps and militias it backs, reportedly killing nearly 40.

The violence has added to concerns of the potential for further escalation.

Iran, a supporter of Hamas, has so far avoided any direct role in the conflict even as groups it backs have entered the fray from Syria, Iraq, Yemen and Lebanon.

Mahjoob Zweiri, director of the Gulf Studies Centre at Qatar University, did not expect a change in Iran’s approach even after the latest US strikes.

“They keep the enemy behind the borders, far away. They are not interested in any direct military confrontation which might lead to attacks on their cities or their homeland. They will maintain that status quo,” he told Reuters.

Iran’s foreign ministry said the latest attacks on Yemen were “a flagrant violation of international law by the US and Britain,” warning the continuation of such attacks was a “worrying threat to international peace and security”.

The Pentagon has said it does not want war with Iran and does not believe Iran wants war either.

The Houthis, who control swathes of Yemen, say their attacks are in solidarity with Palestinians as Israel strikes Gaza.

The US and its allies characterise them as indiscriminate and a menace to global trade.

Sarea, the Houthi spokesman, suggested in a statement on social media that the group would press on.

“These attacks will not deter us from our ethical, religious and humanitarian stance in support of the resilient Palestinian people in the Gaza Strip,” Sarea said.

Just hours before the latest major wave of strikes from the sea and air, the US military’s Central Command detailed other, more limited strikes in the past day that included hitting six cruise missiles the Houthis were preparing to launch against ships in the Red Sea.

About 4am in Yemen on Sunday, the US military also struck a Houthi anti-ship cruise missile poised to launch.

UK Defence Minister Grant Shapps said this was “not an escalation”.

“We have already successfully targeted launchers and storage sites involved in Houthi attacks, and I am confident that our latest strikes have further degraded the Houthis’ capabilities,” he said.

-AAP