National security adviser Mike Waltz is leaving his White House post, although soon after reports about his departure were published, President Trump announced he plans to nominate him to be ambassador to the United Nations.

Mike Waltz will be nominated as U.S. ambassador to the U.N., while Secretary of State Marco Rubio will take on the added role of interim 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?