US officials on Sunday vowed further strikes in Yemen until the Houthi rebels decide to end their attacks on Red Sea shipping, while also threatening action against Iran.

In a wave of strikes on Saturday, the first against the rebel group since US President Donald Trump returned to office in January, several Houthi leaders were killed, the White House said.

The airstrikes “actually targeted multiple Houthi leaders and took them out”, National Security Advisor Michael Waltz told ABC News. He added that the United States “will hold not only the Houthis accountable, but we’re going to hold Iran, their backers, accountable as well”.

“And if that means their targeting ships that they have put in to help, their Iranian trainers… other things that they have put in to help the Houthis attack the global economy, those targets will be on the table too.”

In a separate appearance on Fox News, he said the strikes “put Iran on notice that enough is enough”.

The US strikes killed at least 31 people and wounded 101, the Yemeni rebel group’s health ministry said on Sunday.

The group, which has controlled much of Yemen for more than a decade, staunchly opposes Israel and the United States and says the shipping attacks are in protest of Israel’s military offensive in Gaza.

The Houthis have launched scores of drone and missile attacks on ships in the Red Sea and Gulf of Aden since the outbreak of the fighting, which was spurred by Hamas’ October 7, 2023 attack on Israel.

US warships have been attacked 174 times and commercial vessels 145 times since 2023, according to the Pentagon, putting a major strain on a sea route that normally carries about 12 percent of world shipping traffic.

Trump, in a lengthy Truth Social post on Saturday announcing the latest attacks, warned Houthi leaders, “Your attacks must stop, starting today. If they don’t, hell will rain down upon you like nothing you have seen before!”

Pentagon chief Pete Hegseth echoed that message on Sunday, vowing an “unrelenting” missile campaign until the Houthi attacks stop.

“I want to be very clear, this campaign is about freedom of navigation and restoring deterrence,” Hegseth said in a televised Fox Business interview.

“The minute the Houthis say, ‘We’ll stop shooting at your ships, we’ll stop shooting at your drones’, this campaign will end. But until then, it will be unrelenting.”

Yemen has seen over a decade of civil war, with the Houthis controlling the capital Sanaa since 2014.

Hegseth, in blunt terms, said the United States was not seeking to get involved in a long Middle East war.

“We don’t care what happens in the Yemeni civil war,” he said. “This is about stopping the shooting at assets in that critical waterway, to reopen freedom of navigation, which is a core national interest of the United States.”

Last month, Trump sent a letter to Iran’s supreme leader Ayatollah Ali Khamenei proposing nuclear talks and saying that in the absence of a deal, the matter could be handled “militarily”.

Tehran chafed at that suggestion, saying it would not negotiate while being “threatened”.

Waltz, in his ABC interview, said flatly: “Iran cannot have a nuclear weapon. All options are on the table to ensure it does not have one.”

He added: “They can either hand it over and give it up in a way that is verifiable, or they can face a whole series of other consequences, but either way, we cannot have a world with the ayatollahs with their finger on the nuclear button. “