WASHINGTON (AP) — U.S. forces carried out a fifth attack Thursday against Iran-backed military sites of Yemen’s Houthi rebels, as President Joe Biden acknowledged that American and British bombings have not yet stopped the militants’ attacks on ships in the Red Sea would have disrupted global shipping.

The latest strikes destroyed two Houthi anti-ship missiles that were “aimed at the southern Red Sea and primed for launch,” U.S. Central Command said in a statement posted on X, formerly known as Twitter. They were carried out by Navy F/A-18 fighter jets, the Pentagon said.

Biden said the U.S. would continue attacks, although it had so far failed to stop the Houthis from continuing to attack commercial and military vessels.

“If you say they are working, are they stopping the Houthis? No. Will they continue, yes,” Biden said in an exchange with reporters before leaving the White House for a domestic policy speech in North Carolina.

Biden’s comments followed another significant round of attacks on Wednesday evening, when the US military fired another wave of ship and submarine missile strikes against 14 Houthi-controlled sites. The attacks were launched from the Red Sea and hit 14 missiles, which the command had also classified as an imminent threat.

His government has also placed the Houthis back on the list of specially designated global terrorists. The sanctions associated with the formal designation are intended to cut off violent extremist groups from their sources of funding while allowing vital humanitarian aid to continue to flow to impoverished Yemenis.

Despite sanctions and military strikes, including a large-scale operation by American and British warships and fighter jets that hit more than 60 targets across Yemen, the Houthis continue to harass commercial and military vessels. The US has strongly warned Iran to stop supplying arms to the Houthis.

“We never said the Houthis would stop immediately,” Pentagon deputy press secretary Sabrina Singh said at a briefing when asked why the attacks did not appear to have stopped the Houthis. Since the start of the joint US-UK operation last Friday, in which 28 locations and more than 60 targets were struck in the first round, the Houthis’ attacks have been “smaller in scale”, Singh said.

For months, the Houthis have claimed attacks on ships in the Red Sea that they say are either linked to Israel or bound for Israeli ports. They say their attacks are aimed at ending Israel’s air and ground offensive in the Gaza Strip, which was sparked by the Palestinian militant group Hamas’ October 7 attack in southern Israel. But the connections to the target ships of the rebel attacks become weaker and weaker the longer the attacks last.

The attacks have also raised questions about whether the conflict between Israel and Hamas has already escalated into a larger regional war.

“We are not seeking war, we do not believe we are at war. We don’t want to see a regional war,” Singh said.

The British military is warning of a possible new attack on ships around 160 kilometers (100 miles) off the coast of Yemen in the Gulf of Aden. The British Maritime Trade Organization, which issues warnings about shipping in the Middle East, did not immediately comment.

Separately, the US and its allies have formed Operation Prosperity Guardian to protect shipping traffic, and warships from the US, France and the UK are currently patrolling the area.

“These attacks will continue for as long as necessary,” National Security Council spokesman John Kirby said Thursday, adding: “I will not demonstrate strikes one way or the other.”

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Associated Press writers Jon Gambrell in Jerusalem and Tara Copp, Lolita C. Baldor and Sagar Meghani contributed to this report.