US President Donald Trump ordered a series of air strikes on Yemen’s Houthi rebels in the country’s capital Sanaa on Saturday. Trump pledged to use “overwhelming lethal force" until the Iranian-backed Houthi group ceased their attacks on shipping in the Red Sea. The group claimed nine 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. The Houthis reported a series of explosions in their territory Saturday evening, with images showing plumes of black smoke over the area of the Sanaa airport complex. The Houthis said the airstrikes would not deter their attacks on shipping in the waters off Yemen, and vowed retaliation on the US. The airstrikes come a few days after the rebel group said it would resume attacks on Israeli vessels in response to Israel's blockade on Gaza. The Houthis 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 a tenuous ceasefire in Gaza took effect. The United States, Israel and Britain have previously hit Houthi-held areas in Yemen. Saturday's operation against the Houthis was conducted solely by the US, the Associated Press reported. It was the first strike on the Yemen-based Houthis under the second Trump administration. Pre-planned missile strikes against the Houthis were carried out multiple times by the Biden administration in response to Houthi attacks on shipping in the region. Trump announced the strikes as he spent the day at his Trump International Golf Club in West Palm Beach, Florida. He said: “These relentless assaults have cost the U.S. and World Economy many BILLIONS of Dollars while, at the same time, putting innocent lives at risk.”