West Palm Beach, Florida. US President Donald Trump said he ordered a series of airstrikes on the Houthi-held areas in Yemen 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 said at least 18 civilians were killed.

“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. It comes two weeks after the US leader sent a letter to Iranian leaders offering a path to restarting bilateral talks between the countries on Iran’s advancing nuclear program. Trump has said he will not allow it to become operational.

The Houthis reported explosions in their territory Saturday evening, in the capital of Sanaa and the northern province of Saada, the rebels’ stronghold on the border with Saudi Arabia, with more airstrikes reported in those areas early Sunday. Images online showed plumes of black smoke over the area of the Sanaa airport complex, which includes a sprawling military facility. The Houthis also reported airstrikes early Sunday on the provinces of Hodeida, Bayda, and Marib.

At least 18 people were killed, including 13 in Sanaa and five in Saada, according to the Houthi-run health ministry. At least 24 others were wounded, including nine in Sanaa and 15 in Saada, it said.

A US official said this was the beginning of air strikes on Houthi targets that are expected to continue. The official spoke on the condition of anonymity because they were not authorized to talk to the press.

Nasruddin Amer, deputy head of the Houthi media office, said the airstrikes won’t deter them and they would retaliate against the US “Sanaa will remain Gaza’s shield and support and will not abandon it no matter the challenges,” he added on social media.

Another spokesman, Mohamed Abdulsalam, on X, called Trump’s claims that the Houthis threaten international shipping routes “false and misleading.”

The airstrikes come a few days after the Houthis said they would resume attacks on Israeli vessels sailing off Yemen in response to Israel’s latest blockade on Gaza. They described the warning as affecting the Red Sea, the Gulf of Aden, the Bab el-Mandeb Strait and the Arabian Sea.

There have been no Houthi attacks reported since then.

Earlier this month, Israel halted all aid coming into Gaza and warned of “additional consequences” for Hamas if their fragile ceasefire in the war isn’t extended as negotiations continue over starting a second phase.

The Houthis had targeted over 100 merchant vessels with missiles and drones, sinking two vessels and killing four sailors, during their campaign targeting military and civilian ships between the start of the war between Israel and Hamas in late 2023 and January of this year, when this ceasefire in Gaza took effect.

The attacks raised the Houthis’ profile as they faced economic and other problems at home amid Yemen’s decade-long stalemated war that’s torn apart the Arab world’s poorest nation.

The Houthi media office said the US strikes hit a residential neighborhood in Sanaa’s northern district of Shouab. Residents said at least four airstrikes rocked the Eastern Geraf neighborhood there, terrifying women and children.

“The explosions were very strong,” said Abdallah al-Alffi. “It was like an earthquake.”

The Eastern Geraf is home to Houthi-held military facilities and a headquarters for the rebels' political bureau, located in a densely populated area.

The Houthis reported fresh strikes on the southwestern Dhamar province late Saturday. They said the strikes hit the outskirts of the provincial capital, also named Dhamar, and the district of Abs.

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

However, Saturday's operation 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.

Such broad-based 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, are in the Red Sea and were part of Saturday's mission. The USS Georgia cruise missile submarine has also been operating in the region.