P resident Donald Trump is replacing his National Security Adviser, Mike Waltz, and nominating him to be Ambassador to the United Nations, he announced Thursday, marking the first major personnel shake-up of Trump’s second term.

Call it foreshadowing. President Donald Trump left Mike Waltz stranded on the tarmac after Air Force One headed for Michigan on Tuesday, just two days before he was fired as national security adviser.

Mike Waltz, who played a central role in the Signal-gate, is now out as Trump's National Security Advisor, but why did he decide to resign?