The Iran-backed Huthis say their missile and drone strikes on passing container ships are in support of Palestinians in the Gaza war raging between Israel and militant group Hamas since October 7.

US Defense Secretary Lloyd Austin condemned the "unprecedented" spate of attacks in waters leading to the Suez Canal, a chokepoint for about 10 percent of global trade, that have forced many shipping companies to divert their vessels.

The task force, which Austin first announced late Monday, would include warships from the United States as well as Britain, Canada, France, Italy, the Netherlands, Norway and other countries.

The Pentagon chief, in Qatar on Tuesday after an Israel visit, told a virtual meeting with 43 countries, the EU and NATO that the attacks "threaten the free flow of commerce".

He urged other nations "to join US-led and other international initiatives... to restore security in the Red Sea to deter future Huthi aggression," the Pentagon said.

The Huthis voiced defiance and pledged to continue the attacks in the Bab al-Mandeb strait, a vital shipping lane between Asia and Europe.

"Even if America succeeds in mobilising the entire world, our military operations will not stop... no matter the sacrifices it costs us," senior Huthi official Mohammed al-Bukhaiti said on X, formerly Twitter.

The Huthis will only halt attacks if Israel's "crimes in Gaza stop and food, medicine and fuel are allowed to reach its besieged population," said Bukhaiti.

Rebel spokesman Mohammed Abdul Salam said the "US-formed coalition aims to protect Israel and militarise the sea. Whoever seeks to expand the conflict must bear the consequences of those actions."