The Houthis — who have already faced multiple rounds of air strikes in response to their targeting of international shipping — struck a US-owned bulk cargo carrier in the wake of the designation announcement, and vowed to continue attacks they say are in support of Palestinians in Gaza.

US forces “conducted strikes on 14 Iran-backed Houthi missiles that were loaded to be fired in Houthi-controlled areas in Yemen,” Central Command (CENTCOM) said in a statement.

“These missiles on launch rails presented an imminent threat to merchant vessels and US Navy ships in the region and could have been fired at any time, prompting US forces to exercise their inherent right and obligation to defend themselves,” CENTCOM said.

Earlier on Wednesday, the United States announced that it would return the Houthis to a list of “terrorist” entities.

“The Department of State today is announcing the designation of Ansarallah, commonly referred to as the Houthis, as a Specially Designated Global Terrorist group, effective 30 days from today,” Secretary of State Antony Blinken said in a statement.

“During the 30-day implementation delay, the US government will conduct robust outreach to stakeholders, aid providers, and partners who are crucial to facilitating humanitarian assistance and the commercial import of critical commodities in Yemen,” he said.

US-owned ship targeted

US National Security Advisor Jake Sullivan said the designation “is an important tool to impede terrorist funding to the Houthis, further restrict their access to financial markets, and hold them accountable for their actions.”

“If the Houthis cease their attacks in the Red Sea and Gulf of Aden, the United States will immediately reevaluate this designation,” Sullivan said in a statement.

The Houthis, however, said they will not call off their strikes.

“We will not give up targeting Israeli ships or ships heading towards ports in occupied Palestine… in support of the Palestinian people,” the group’s spokesman Mohammed Abdelsalam told Al Jazeera TV, adding that they would respond to new strikes on Yemen by the United States or Britain.

While the Houthis say they have been attacking Israeli-linked vessels, Washington says dozens of countries have connections to the ships that have been targeted.