WASHINGTON (AP) — U.S. fighter jets struck Iranian-backed Houthi rebel sites for the sixth time Friday, taking out anti-ship missile launchers in Yemen that were prepared to fire, according to two U.S. officials.

The officials, who spoke on condition of anonymity to discuss ongoing military operations, said the strikes were carried out by F/A-18 aircraft off the USS Dwight D. Eisenhower aircraft carrier. And they resembled similar U.S. attacks on Houthi launchers that have been occurring almost daily this week.

President Joe Biden acknowledged Thursday that the bombardment of Houthi sites, including a massive array of strikes on Jan. 12 by U.S. and British forces, has yet to stop the militants’ attacks on vessels in the Red Sea that have disrupted global shipping.

Al-Masirah, a Houthi-run satellite news channel, said there were air raids in the western city of Hodieda on Friday, targeting the al-Jabaana neighborhood in the west of the city. The location of the U.S. strikes could not be immediately confirmed.

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U.S. warships and aircraft, in rapid succession, have taken out Houthi missiles poised to launch over the past few days, underscoring the military’s increasing ability to watch, detect and strike militant activities in Yemen. But so far the strikes have not deterred Houthi attacks on ships in the southern Red Sea or Gulf of Aden, which also have been happening nearly daily.

The Biden administration 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, while also allowing vital humanitarian aid to continue flowing to impoverished Yemenis.

And the White House has made it clear that U.S. retaliatory strikes will also be persistent.

“These strikes will continue for as long as they need to continue,” National Security Council spokesman John Kirby said Thursday, adding, “I’m not going to telegraph punches one way or another.”

For months, the Houthis have attacked ships in the Red Sea that they say are either linked to Israel or heading to Israeli ports. They say their attacks aim to end the Israeli air-and-ground offensive in the Gaza Strip that was triggered by the Palestinian militant group Hamas’ Oct. 7 attack in southern Israel. But the links to the ships targeted in the rebel assaults have grown more tenuous as the attacks continue.