Donald Trump said he ordered a series of airstrikes on Yemen’s capital, Sana’a, on Saturday, promising to use “overwhelming lethal force” until Iranian-backed Houthi rebels cease their attacks on shipping along a vital maritime corridor.

The Houthis reported a series of explosions in their territory on Saturday evening. Images circulating online show plumes of black smoke over the area of the Sana’a airport complex, which includes a sprawling military facility. The extent of the damage was not yet clear.

“Our brave Warfighters are right now carrying out aerial attacks on the terrorists’ bases, leaders, and missile defenses to protect American shipping, air, and naval assets, and to restore Navigational Freedom,” Trump said in a social media post.

“No terrorist force will stop American commercial and naval vessels from freely sailing the Waterways of the World.”

He also warned Iran to stop supporting the rebel group, promising to hold the country “fully accountable” for the actions of its proxy.

The airstrikes come a few days after the Houthis said they would resume attacks on Israeli vessels sailing in waters off Yemen in response to Israel’s blockade on Gaza. There have been no Houthi attacks reported since then.

At least 13 civilians were killed and nine injured in the US strikes on Sana’a, the Houthi-run health ministry said on Saturday evening.

Six other people, including four children and one woman, were killed and 11 were injured in a US strike on the northern province of Sa’ada, Houthi-run al-Masirah TV reported.

The Houthi rebels have targeted more than 100 merchant vessels with missiles and drones, sinking two vessels and killing four sailors during their campaign targeting military and civilian ships after the start of the war between Israel and Hamas in late 2023 until January of this year, when a tenuous ceasefire in Gaza took effect.

The attacks greatly raised the Houthis’ profile as they faced economic problems and launched a crackdown targeting any dissent and aid workers at home amid Yemen’s decade-long stalemated war that has torn apart the Arab world’s poorest nation.

The United States, Israel and Britain have previously hit Houthi-held areas in Yemen. Israel’s military declined to comment.

The Houthi media office said the US strikes hit “a residential neighborhood” in Sana’a’s northern district of Shouab.

The Saturday operation against the Houthis was conducted solely by the US, according to a US official. It was the first strike on the Yemen-based Houthis under the second Trump administration, and it comes after a period of relative quiet in the region.

Such broad-based and pre-planned missile strikes against the Houthis were carried out multiple times by the Biden administration in response to frequent attacks by the Houthis against commercial and military vessels in the region.

The USS Harry S Truman carrier strike group, which includes the carrier, three navy destroyers and one cruiser, is in the Red Sea and was part of the mission. The USS Georgia cruise missile submarine has also been operating in the region.

Trump announced the strikes as he spent the day at his Trump International Golf Club in West Palm Beach, Florida.

“These relentless assaults have cost the US and World Economy many BILLIONS of Dollars while, at the same time, putting innocent lives at risk,” Trump said.