Trump says he is nominating Mike Waltz to serve as U.N. ambassador

President Trump posted on social media that he intends to nominate Mike Waltz to serve as the next ambassador to the United Nations, a role Rep. Elise Stefanik, R-N.Y., was nominated for before being withdrawn to continue her work in Congress. NBC News' Garrett Haake reports from the White House as the post comes just hours after news broke that Waltz would be stepping down from his position as Trump's national security adviser.