Overview

Background

Waltz was born on January 31, 1974, in Boynton Beach, Florida. He graduated from the Virginia Military Institute with honors before embarking on a military career that spanned active duty and the National Guard. In Congress, he served as a subcommittee chairman on the House Armed Services Committee, Foreign Affairs Committee, and Permanent Select Committee on Intelligence. Those assignments placed him at the center of Republican thinking on defense and foreign affairs during the Biden years, and he became a vocal critic of what he characterized as insufficient U.S. resolve on China and counterterrorism.

In Congress, he chaired the Readiness subcommittee of the House Armed Services Committee and served on the Foreign Affairs Committee and the Permanent Select Committee on Intelligence. He also served on the China and Trump Assassination Task Forces before stepping down from his seat to serve in the Trump administration. His record placed him squarely in the hawkish wing of the Republican Party — a positioning that would later become a source of tension inside the White House.

Public Role in the Second Trump Administration

National Security Adviser

Waltz was sworn in as President Trump's national security adviser on January 20, 2025. The national security adviser role does not require Senate confirmation, and Waltz took the position with broad support among Republican national security professionals. His tenure, however, lasted only about three and a half months. The administration's priorities sometimes sat awkwardly with his more interventionist instincts, and according to reporting by The New York Times, most of Trump's advisers already considered Waltz "too hawkish" in an administration that has signaled openness to diplomacy, including with Iran.

Signalgate

The episode most associated with Waltz's NSC tenure was the so-called Signalgate affair. He generated widespread negative coverage when he accidentally added the editor of The Atlantic, Jeffrey Goldberg, to a March 2025 Cabinet-level group chat about classified military plans to strike Houthi rebels in Yemen, using the Signal messaging app. The app is generally not an authorized form of high-level government communication. Waltz took full responsibility for adding Goldberg to the chat. Trump did not immediately dismiss Waltz, insisting he had "learnt a lesson, and he's a good man." Nevertheless, the incident weakened Waltz's standing inside the White House and intensified pressure from MAGA-aligned voices who had already questioned his ideological fit.

Waltz was also under siege from figures such as right-wing activist Laura Loomer, who had been complaining to administration officials that she had been excluded from the vetting process for National Security Council aides and argued that Waltz relied too much on hawkish neoconservatives and others who were "not-MAGA-enough." As reports began to circulate that Waltz was leaving, Loomer appeared to take credit in a post on X, writing "SCALP."

Removal and Nomination to the UN

Trump announced on May 1, 2025, that he would nominate Waltz to serve as UN ambassador, in the first major staff shakeup since the president took office in January. Rubio became the first person since Henry Kissinger in the 1970s to hold the positions of secretary of state and national security adviser simultaneously. The move was widely read as a soft landing for Waltz — a way to remove him from the NSC without a complete break. Foreign officials, including some from the Middle East, expressed apprehension about the change; one senior western official said: "Of all of them, we never thought he would be the first to be fired."

As UN Ambassador

Waltz's confirmation hearing before the Senate Foreign Relations Committee came months after he exited the White House amid the Signal controversy. Democratic Senator Tammy Duckworth of Illinois had promised a "brutal, brutal hearing" and described the nomination as "failing up." Despite the opposition, Waltz was confirmed and sworn in as the 32nd U.S. Representative to the United Nations on September 20, 2025.

At the UN, Waltz has pursued an agenda closely aligned with the America First framework. He has spearheaded efforts to reduce wasteful spending and streamline peacekeeping missions, including what the administration has described as the UN's first major budget cut in its existence. In testimony before the Senate Foreign Relations Committee in April 2026, he noted that the 2026 UN regular budget was estimated at $3.45 billion and that the U.S. funds roughly a fifth of that — approximately $820 million in 2025 alone. Waltz has used that financial leverage as a negotiating tool, arguing that American contributions warrant both institutional reform and greater deference to U.S. priorities.

Waltz has also positioned himself as a leading voice against what he describes as anti-American and antisemitic bias at the UN, and has championed international religious freedom and the plight of persecuted Christian communities. At his confirmation hearing, he argued that it was "absurd" that China is treated as a developing nation within UN agencies and urged action against what he called "pervasive" antisemitism, citing what he described as a dramatic disparity between UN resolutions against Israel and those against other nations.

Waltz has also worked from his post in New York to build broad international coalitions to address crises in Gaza, Haiti, and Sudan, as well as threats to maritime security and global commerce in the Middle East.

Recent Developments

In April 2026, Waltz testified before the Senate Foreign Relations Committee on UN reform, framing his work as an ongoing effort to make the organization leaner and more accountable. He has argued that the UN should be doing less and doing it better — getting more focused and actually achieving more results. Through what is known as the UN's Fifth Committee, which approves its budget, the U.S. has been working toward a leaner and better-prioritized 2026 budget.

One significant diplomatic question on Waltz's horizon involves the succession to UN Secretary-General António Guterres. The most enduring mark that the Trump administration may leave on the United Nations could be steering the selection of Guterres's successor; his term concludes at the end of 2026, and the successful candidate will need at least nine Security Council votes without a veto from any of the five permanent members. That dynamic gives the United States, through Waltz, considerable influence over who leads the institution next.

Outlook

Waltz enters the second half of Trump's second term in a more stable institutional position than he occupied at the NSC. His confirmation to the UN post gave him a Senate mandate that his earlier White House role lacked, and his priorities — budget discipline, countering Chinese influence, and challenging perceived UN bias against Israel — map closely onto the administration's broader foreign policy posture. Whether he can translate those priorities into durable institutional changes remains an open question, particularly given how quickly alliances and agendas can shift in Trump-era governance. The UN secretary-general succession process will be an early test of how much real leverage the United States, and Waltz personally, can exercise in New York.