The Huthis began targeting shipping in the Red Sea and Gulf of Aden in late 2023 and the United States responded with strikes against them starting early the following year.

In the latest round of its air campaign since March 15, "USCENTCOM strikes have hit over 1,000 targets, killing Huthi fighters and leaders... and degrading their capabilities", Pentagon spokesman Sean Parnell said in a statement on Tuesday, referring to the military command responsible for the Middle East.

On Wednesday Britain said it had joined the United States in carrying out strikes against Huthi targets.

"UK forces participated in a joint operation with US forces against a Huthi military target in Yemen," the defence ministry said in a statement.

It said the Royal Air Force had struck buildings around 25 kilometers (15 miles) south of the capital Sanaa at night, which it said were being used by Huthi rebels to manufacture drones.

British defence minister John Healey told the UK's parliament later on Wednesday "our initial assessment is that the planned targets were all successfully hit, and we've seen no evidence of civilian casualties."

He said the Huthis had launched "over 320 attacks" targeting international shipping in the Red Sea since November 2023.

Britain has taken part in joint air strikes against Huthis led by the United States since early 2024.

CENTCOM on Sunday had said US strikes hit more than 800 targets since mid-March, saying hundreds of Huthi fighters had been killed as a result.

Hours after that announcement, Huthi-controlled media said US strikes had hit a migrant detention center in the city of Saada, killing at least 68 people, while a United Nations spokesperson later said preliminary information indicated that those killed were migrants.

A US defense official said the military was looking into reports of civilian casualties resulting from its strikes in Yemen.

Attacks by the Iran-backed Huthis have prevented ships from passing through the Suez Canal -- a vital route that normally carries about 12 percent of the world's shipping traffic.

The rebels say they are targeting shipping in solidarity with Palestinians in Gaza, which has been devastated by Israel's military after a shock Hamas attack in October 2023.