Washington, United States — US President Donald Trump confirmed Thursday that he was replacing his national security advisor Mike Waltz following a chat group leak, saying he planned to move him to the United Nations.

In the first major cabinet shake-up of Trump's new term, the president said Secretary of State Marco Rubio would now also serve as his "interim" national security advisor following Waltz's departure.

"I am pleased to announce that I will be nominating Mike Waltz to be the next United States Ambassador to the United Nations," Trump said on Truth Social, confirming earlier reports that Waltz was being ousted.

"Mike Waltz has worked hard to put our Nation's Interests first. I know he will do the same in his new role."

Trump did not give a reason for the move but Waltz had been under pressure over the so-called "Signalgate" scandal since late March.

The editor-in-chief of The Atlantic magazine revealed at the time that Waltz had mistakenly added him to a group chat about US strikes on Yemen's Huthi rebels on the commercial messaging app Signal.

Officials on the group laid out the attack plan, including the timings that US warplanes would take off to bomb targets, with the first texts barely half an hour before they launched.

Despite intense media speculation that Trump would fire Waltz over the scandal, the president repeatedly offered his backing and the national security advisor appeared to have ridden out the storm.

In the end, however, the 51-year-old former congressman from Florida lasted just over 100 days of Trump's second term, which has so far been more stable in terms of personnel than his first.

Democrats will now turn up the heat on Defense Secretary Pete Hegseth, who was the official who revealed the air strike details in advance, and who was also reported to have shared those details in a separate Signal group chat that included, among others, his spouse.

"Now do Hegseth," top Senate Democrat Chuck Schumer posted on X.

Waltz's new role will also require Senate confirmation, ensuring that Signalgate will stay in the headlines.

There was no immediate confirmation of US media reports that Waltz's deputy, Alex Wong, would also leave the National Security Council.

US media had reported that Steve Witkoff, a real estate magnate whom Trump has picked to lead US talks with both Russia and Iran, is in contention to replace Waltz in the longer term.

'SCALP'

Waltz was among a number of White House staff targeted by right-wing influencer and conspiracy theorist Laura Loomer, who met with Trump urging a purge.

Loomer, who is known for claiming that the 11 September 2001, attacks were an inside job, is reported to have successfully pushed for the dismissal of several senior US security officials she deemed disloyal to the president.

After news of Waltz's ouster was reported Thursday, Loomer appeared to take credit in a post on X, saying: "SCALP."

Waltz showed no sign that he knew of his imminent departure when appearing early Wednesday on Fox News, where he hailed the new US minerals deal with Ukraine.

Waltz was also present at Trump's televised cabinet meeting on Wednesday when he lavished praise on the president.

"We've had 100 days of your leadership with respect, with strength," Waltz said. "It's an honor to serve you in this administration."

A former special forces officer, Waltz was seen as a moderate voice in the Trump administration when he was appointed, but reportedly clashed with other officials over his hawkish stance against Russia and Iran.

Trump has pushed for Ukraine to reach a quick ceasefire deal with Russia, while reopening negotiations with Iran over its nuclear program.

The National Security Advisor's role has been held in the past by some of the most high-profile officials in US history, including Henry Kissinger.

But Waltz had been on borrowed time since Signalgate emerged as the first major scandal of the whirlwind start of Trump's new term.

On the text chain, Waltz sent real-time intelligence on the aftermath of an attack on the Huthis, writing that US forces had identified the target "walking into his girlfriend's building and it's now collapsed."

Hegseth revealed detailed timings of the US airstrikes on Yemen, putting him squarely in the Democrats' crosshairs.

(Source: Danny KEMP, AFP)