President Donald Trump announced Thursday that White House National Security Adviser Mike Waltz will be nominated as the next U.S. Ambassador to the United Nations. The move represents the first major personnel shift in Trump’s newly re-elected administration since it began in January.

While the nomination process for Waltz is underway, Trump confirmed that U.S. Secretary of State Marco Rubio will temporarily assume the role of National Security Advisor. Rubio will continue to lead the State Department while holding the national security role on an interim basis.

Waltz’s reassignment follows his involvement in a March scandal, where he inadvertently added Atlantic journalist Jeffrey Goldberg to a private Signal chat group intended for White House staff. Although no classified information was reportedly exposed, the incident drew criticism and raised concerns about internal security protocols.

Further pressure mounted this week as reports surfaced of growing friction between Waltz and other White House personnel, particularly Chief of Staff Susie Wiles. Axios reported Thursday that tensions had escalated in recent weeks, prompting speculation about changes in the national security team.

Trump’s decision to elevate Waltz to the UN post while shifting Rubio into the national security role signals a calculated rebalancing of leadership. The administration appears to be consolidating experienced figures into key posts amid a complex global landscape.

The White House has yet to announce a permanent replacement for the National Security Advisor position following Rubio’s interim service. Confirmation proceedings for Waltz’s UN appointment are expected to begin in the coming weeks.