President Joe Biden said on Saturday the United States had delivered a private message to Iran about Iran-backed Houthis responsible for attacking commercial shipping in the Red Sea.

“We delivered it privately and we’re confident we’re well-prepared,” Biden told reporters at the White House before departing to the Camp David presidential retreat for the weekend.

The Houthi movement threatened a “strong and effective response” after the United States carried out another strike in Yemen overnight, further ratcheting up tensions as Washington vows to protect shipping from attacks by the Iran-aligned group.

The latest strike, which the U.S. said hit a radar site, came a day after dozens of American and British strikes on Houthi facilities in Yemen.

White House spokesperson John Kirby said on Friday the initial strikes had hit the Houthis’ ability to store, launch and guide missiles or drones, which the group has used to threaten shipping.

He said Washington had no interest in a war with Yemen.

Biden, whose administration removed the Houthis from a State Department list of “foreign terrorist organizations” in 2021, was asked by reporters on Friday whether he felt the term “terrorist” described the movement now. “I think they are,” Biden said.