Dhaka, May 1 -- 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 i...