'Well there you go' - watch moment spokeswoman learns Waltz news
State Department spokesperson Tammy Bruce found out about Mike Waltz's job change from a reporter during a press briefing.
US President Donald Trump posted on Truth Social that he will nominate Waltz to be "the next United States Ambassador to the United Nations".
Continuing his post, Trump added that Secretary of State Marco Rubio will also serve as national security adviser in the meantime.
It comes hours after reports said Waltz would step down from his role as national security adviser.