President Trump announced on Thursday that Mike Waltz, who is stepping down from his role as national security adviser, will be his nominee for U.S. ambassador to the United Nations, while Secretary of State Marco Rubio will also taken on national security adviser role.

"I am pleased to announce that I will be nominating Mike Waltz to be the next United States Ambassador to the United Nations. From his time in uniform on the battlefield, in Congress and, as my National Security Advisor, Mike Waltz has worked hard to put our Nation’s Interests first. I know he will do the same in his new role," Trump posted on Truth Social on Thursday.

"In the interim, Secretary of State Marco Rubio will serve as National Security Advisor, while continuing his strong leadership at the State Department. Together, we will continue to fight tirelessly to Make America, and the World, SAFE AGAIN. Thank you for your attention to this matter!"