The US on Saturday launched a wave of air strikes against Houthi rebels in Yemen, as Donald Trump warned that “hell will rain down upon” the Iran-backed group if they continue to attack shipping in the Red Sea.

The US president also warned Iran to halt its support for the militant group “immediately”.

The attacks came days after the Houthis, which control most of Yemen’s populous north, threatened to resume attacks on shipping in the Red Sea and Gulf of Aden.

“Today, I have ordered the United States Military to launch decisive and powerful Military action against the Houthi terrorists in Yemen,” Trump said in a post on Truth Social. “They have waged an unrelenting campaign of piracy, violence, and terrorism against American, and other, ships, aircraft, and drones”.

The Houthis launched scores of attacks on merchant vessels and US navy ships in the Red Sea last year, saying they were acting in solidarity with Palestinians as Israel carried out its ferocious offensive against Hamas in Gaza.

The assaults severely disrupted traffic through one of the world’s most important maritime trade routes and continued despite US, UK and Israeli air strikes on Houthi military targets in Yemen.

The Houthis halted their campaign after Israel and Hamas agreed to a fragile ceasefire in January under which the Palestinian militants agreed to release hostages seized in their October 7, 2023 assault on the Jewish state.

But the Houthis warned this week that they would resume their attacks on shipping after Israel blocked the delivery of all aid into Gaza in a bid to pressure Hamas to accept a revised proposal for the second phase of the ceasefire deal.

The US air strikes on Saturday targeted Houthis’ leaders, bases and missile defences, Trump said.

“The Houthi attack on American vessels will not be tolerated,” Trump said. “We will use overwhelming lethal force until we have achieved our objective”. 

“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!” Trump added.

Trump on Saturday also warned Tehran against supporting the Yemeni rebels, which are part of Iranian-backed militants that make up the so-called “axis of resistance”.

The US and Israel accuse Iran of supplying the Houthis with increasingly sophisticated drone and missile technology, as well as intelligence.

“To Iran: Support for the Houthi terrorists must end IMMEDIATELY!” he said.

“Do NOT threaten the American People, their President, who has received one of the largest mandates in Presidential History, or Worldwide shipping lanes. If you do, BEWARE, because America will hold you fully accountable and, we won’t be nice about it!”

Trump is reimposing his so-called “maximum pressure” campaign against the republic. During his first term, Trump withdrew the US from the 2015 nuclear deal Tehran signed with world powers and imposed hundreds of sanctions on the republic.

He has announced more sanctions on Tehran since returning to the White House, while also saying he wants to negotiate with Iran on its nuclear programme. But he has also held out the threat of military action.

His administration has also designated the Houthis a foreign terrorist organisation as it looks to step up the pressure on the Yemeni rebel group.

The Houthi-run health ministry said that at least nine civilians were killed and nine wounded in the US strikes on Sana’a, Yemen’s capital.

The Houthis have controlled Sana’a and most of the north for a decade since ousting the Yemeni government as the impoverished Arab state descended into civil war.

The conflict drew in Saudi Arabia and the United Arab Emirates, which led an Arab coalition that intervened to fight the Houthis in March 2015.

Saturday’s strikes were the most significant military actions taken by Trump since he returned to the White House.

“The conflict between the Houthis in Yemen and the United States of America has reached a new level of intensity, with US air strikes tonight marking a significant shift,” said Mohammed Al-Basha, founder of Basha Report, a US-based consultancy.

“From now on, it’s gloves off between the Houthis and Centcom,” he added, referring to the US military command.

Yemen’s embassy in Washington and Iran’s mission to the United Nations did not immediately respond to requests for comment.