People gather at the site of a house hit by a US strike in Saada, Yemen March 16, 2025. Photo: REUTERS/Naif Rahma

The United States will keep attacking Yemen’s Houthis until they end attacks on shipping, the US defense secretary said on Sunday, as the Iran-aligned group signaled it could escalate in response to deadly US strikes the day before.

The airstrikes, which killed at least 31 people, are the biggest US military operation in the Middle East since President Donald Trump took office in January. One US official told Reuters the campaign might continue for weeks.

The Houthi movement’s political bureau described the attacks as a “war crime” and said Houthi forces were ready to “meet escalation with escalation,” while Moscow urged Washington to cease the strikes.

US Defense Secretary Pete Hegseth told Fox News: “The minute the Houthis say we’ll stop shooting at your ships, we’ll stop shooting at your drones, this campaign will end, but until then it will be unrelenting.”

“This is about stopping the shooting at assets… in that critical waterway, to reopen freedom of navigation, which is a core national interest of the United States, and Iran has been enabling the Houthis for far too long,” he said. “They better back off.”

The Houthis, who have taken control of most of Yemen over the past decade, said last week they would resume attacks on Israeli ships passing through the Red Sea if Israel did not lift a block on aid entering Gaza.

They had launched scores of attacks on shipping after Israel’s war with Hamas began in late 2023, saying they were acting in solidarity with Gaza’s Palestinians.

Trump also told Iran, the Houthis’ main backer, to stop supporting the group immediately. He said if Iran threatened the United States, “America will hold you fully accountable and, we won’t be nice about it!”

IRAN WARNS US NOT TO ESCALATE

In response, Hossein Salami, the top commander of Iran’s Revolutionary Guards, said the Houthis made their own decisions.

“We warn our enemies that Iran will respond decisively and destructively if they carry out their threats,” he told state media.

US Secretary of State Marco Rubio told CBS News’ “Face the Nation” program:

“There’s no way the … Houthis would have the ability to do this kind of thing unless they had support from Iran. And so this was a message to Iran: don’t keep supporting them, because then you will also be responsible for what they are doing in attacking Navy ships and attacking global shipping.”

Russian Foreign Minister Sergei Lavrov called Rubio to urge an “immediate cessation of the use of force and the importance for all sides to engage in political dialogue,” Moscow said.

Trump has been pressing Russia to sign a US proposal for a 30-day ceasefire in its war with Ukraine, which Kyiv accepted last week, but Moscow has said it needs to be reworked.

Trump is also increasing sanctions pressure, and hoping to enlist Russian help, to try to bring Tehran to the negotiating table over its nuclear program.

Most of the 31 people confirmed killed in the US strikes were women and children, said Anees al-Asbahi, spokesperson for the Houthi-run health ministry. More than 100 were injured.

Residents in Sanaa said the strikes hit a neighborhood known to host several members of the Houthi leadership.

“The explosions were violent and shook the neighborhood like an earthquake. They terrified our women and children,” said one of the residents, who gave his name as Abdullah Yahia.

In Sanaa, a crane and bulldozer were used to remove debris at one site and people used their bare hands to pick through the rubble. At a hospital, medics treated the injured, including children, and the bodies of several casualties were placed in a yard, wrapped in plastic sheets, Reuters footage showed.

Strikes also targeted Houthi military sites in the city of Taiz, two witnesses said on Sunday.

HOUTHIS’ RED SEA ATTACKS DISRUPT GLOBAL TRADE ROUTE

Another strike, on a power station in the town of Dahyan, led to a power cut, Al-Masirah TV reported early on Sunday. Dahyan is where Abdul Malik al-Houthi, the enigmatic leader of the Houthis, often meets visitors.

The Houthi attacks on shipping have disrupted global commerce and set the US military off on a costly campaign to intercept missiles and drones.

The group suspended its campaign when Israel and Hamas agreed to a ceasefire in Gaza in January.

But on March 12, the Houthis said their threat to attack Israeli ships would remain in effect until Israel re-approved the delivery of aid and food into Gaza.

Joe Biden’s previous US administration had also sought to degrade the Houthis’ strike power. But US officials, speaking on condition of anonymity, said Trump had authorized a more aggressive approach.

The US military’s Central Command described Saturday’s strikes as the start of a large-scale operation across Yemen.

The strikes were carried out in part by fighter aircraft from the aircraft carrier Harry S. Truman in the Red Sea, officials said.

Iran condemned the strikes as a “gross violation” of the U.N. Charter and international law.

Iranian Foreign Minister Abbas Araqchi said the US government had “no authority, or business, dictating Iranian foreign policy.”