【Trump Announces Nomination of Mike Waltz as the Next U.S. Ambassador to the United Nations】 Golden Finance reports that on May 1st local time, U.S. President Trump posted on social media to announce the nomination of Mike Waltz as the next U.S. Ambassador to the United Nations. U.S. Secretary of State Rubio will also serve as National Security Advisor while continuing his role at the State Department. Earlier that day, several informed sources revealed that U.S. National Security Advisor Mike Waltz and his deputy Alex Huang are about to leave their positions.