Trump ousts Waltz as national security adviser

US President Donald Trump has removed Mike Waltz from his post as national security adviser, and is going to nominate him as ambassador to the United Nations.

In a post on social media, Trump thanked Waltz for his work and said he would be temporarily replaced by Secretary of State Marco Rubio, who will continue as America's top diplomat, according to a BBC report.

Waltz had faced criticism for mistakenly adding a journalist to a chat group where sensitive military plans were discussed - a political embarrassment likely to feature during confirmation hearings for the UN post.

The former Florida congressman is the first senior member of the administration to leave the White House in Trump's second term.

"From his time in uniform on the battlefield, in Congress and, as my National Security Advisor, Mike Waltz has worked hard to put our Nation's Interests first," Trump wrote in a post on Truth Social.

"I know he will do the same in his new role."

According to the BBC's US partner CBS News, Trump decided to nominate Waltz as UN ambassador just hours before the announcement on Thursday.

Multiple sources told the network he was ousted because of the Signal situation and a perception in the White House that he did not properly vet National Security Council staff, among other reasons.

But the sources said Trump respects Waltz so he was given a soft landing and a high-profile new post.

However, the BBC spoke to several US officials - who wished to remain anonymous - and they suggested the Trump administration believed Waltz might struggle to be confirmed by the Senate, allowing the president to get rid of him completely without having to fire him.

Waltz has been under scrutiny since he acknowledged in March mistakenly adding the editor-in-chief of the Atlantic magazine, Jeffrey Goldberg, to a group chat on Signal with top US security officials.

Confidential plans for a military strike on Yemen's Houthis were discussed on the message chain, whose members included Waltz, Rubio and Defence Secretary Pete Hegseth.

There was uncertainty on Thursday over the fate of Waltz's deputy, Alex Wong, a seasoned foreign policy hand from Trump's first term who was also on the Signal chat.