WASHINGTON (AP) President Joe Biden said Thursday that U.S. military strikes against Iranian-back Houthi rebels in Yemen will continue, but he acknowledged that the American and British bombardment has yet to stop shipping attacks by the militants on vessels in the Red Sea.

Biden said the U.S. would continue the strikes in an exchange with reporters before departing the White House for a domestic policy speech in North Carolina.

When you say working, are they stopping the Houthis, no. Are they going to continue, yes, Biden said.

The U.S. military fired another wave of ship- and submarine-launch missile strikes against Houthi-controlled sites on Wednesday, marking the fourth time in days it has directly targeted the group in Yemen as violence that ignited in the wake of the Israel-Hamas war continues to spill over in the Middle East.

The strikes were launched from the Red Sea and hit 14 missiles that the command deemed an imminent threat.

The strikes followed an official announcement Wednesday that the U.S. has put the Houthis back on its list of specially designated global terrorists . The sanctions that come with the formal designation are meant to sever violent extremist groups from their sources of financing.

Despite sanctions and military strikes, including a large-scale operation carried out by U.S. and British warships and warplanes that hit more than 60 targets across Yemen, the Houthis keep harassing commercial and military ships. The U.S. has strongly warned Iran to cease providing weapons to the Houthis.