Waltz was on television as late as Thursday morning, promoting the administration’s agreement with Kyiv that would allow the U.S. to access Ukraine’s critical minerals and other natural resources.

Waltz was at the center of the Signal chat controversy, in which a journalist was accidentally included in a discussion of sensitive military information.

Reports of Mike Waltz's exit as national security advisor focused on Signalgate, but President Donald Trump has nominated him to be U.N. ambassador.