In the first major cabinet reshuffle of his second term, President Donald Trump announced on May 1, 2025, that he is removing Mike Waltz from his position as National Security Advisor and nominating him to serve as the United States Ambassador to the United Nations. The president revealed that Secretary of State Marco Rubio would take over as interim National Security Advisor while maintaining his current role at the State Department. This marks a significant shift in Trump's inner circle just months after taking office in January.

The announcement came after widespread speculation about Waltz's future in the administration. Trump informed Waltz of his decision on Thursday morning before making it public through a post on Truth Social. In his statement, Trump praised Waltz's service, noting, "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". Waltz later expressed gratitude on social media, stating he was "honored to continue my service to President Trump and our great nation".

Waltz's departure follows recent controversy surrounding his inadvertent addition of a journalist to a Signal chat group where senior Trump officials, including Defense Secretary Pete Hegseth and CIA Director John Ratcliffe, were discussing military strikes against Yemen terrorists. This incident reportedly frustrated President Trump and led to scrutiny of Waltz's leadership. Fox News confirmed that both Waltz and his deputy, Alex Wong, were removed from their positions, with additional staff dismissals anticipated.

With this appointment, Rubio becomes the first person since Henry Kissinger in the 1970s to simultaneously hold the positions of Secretary of State and National Security Advisor. Trump has expressed confidence in Rubio's abilities, stating at a White House event earlier on Thursday, "When I have an issue, I reach out to Marco. He resolves it". The UN ambassador position had been vacant since Trump withdrew Representative Elise Stefanik's nomination in March, citing the narrow Republican majority in the House of Representatives.