President Trump abruptly fired Kirstjen Nielsen, the Secretary of Homeland Security known as the 'vanguard of immigrant crackdowns'.

This is the first time an incumbent secretary has been replaced since the launch of Trump's second-term administration.

Amid the ongoing large-scale military operations against Iran, the dismissal of the head of the department responsible for homeland security is considered unusual.

With the midterm elections in November approaching and continuous controversies, President Trump seems to be under significant pressure.

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Former President Donald Trump, who was the Republican presidential candidate as of October 14, 2024, and Kristi Noem, Governor of South Dakota, are dancing to the song "Y.M.C.A." at a campaign town hall at the Greater Philadelphia Expo Center & Fairgrounds in Oaks, Pennsylvania. Photo by AP Yonhap News

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U.S. President Donald Trump, Florida Governor Ron DeSantis, and Homeland Security Secretary Kristi Noem toured the new immigrant detention facility, "Alligator Alcatraz," at the Dade-Collier Training and Transition Center in Ochopee, Florida, on July 1, 2025. Photo by AP Yonhap News

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On March 5 (local time), U.S. President Donald Trump announced on his social media platform, Truth Social, "The respected Senator from Oklahoma, Markwayne Mullin, will become the new Secretary of Homeland Security," adding, "I thank Christie Noem for her service." He further stated, "She will move on to serve as Special Envoy for the Shield of the Americas, a new security initiative in the Western Hemisphere." Although this was formally presented as an envoy appointment, the dominant view is that it was actually a disciplinary personnel measure in response to the series of controversies surrounding Secretary Noem in recent times.

On January 24, 2026, then Homeland Security Secretary Christi Nomm delivered a speech at a press conference held at the Federal Emergency Management Agency headquarters in Washington / AP Yonhap News

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Kristi Noem, U.S. Secretary of Homeland Security, is holding a press conference in New York on January 8, 2026. Photo by AP Yonhap News Agency

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Secretary Christie Noem, who has long been considered one of President Trump's most loyal allies, led the anti-immigration policy, a key agenda of the Trump administration. After serving as Governor of South Dakota, she took office as Secretary of Homeland Security in January of last year, overseeing border security for the Trump second-term administration.

However, in January, during an immigration enforcement operation in Minneapolis, Minnesota, two U.S. citizens were killed by agents from the Immigration and Customs Enforcement (ICEUnited States Immigration and Customs Enforcement (ICE).).

This incident triggered a surge of criticism against ICE, the Border Patrol, and the Department of Homeland Security, which oversees them, leading to nationwide protests and controversy. Secretary Noem, in particular, faced intense public backlash for initially labeling the deceased as "terrorists" during her response.

On March 26, 2025, then US Secretary of Homeland Security Kristie Nomm visited a terrorist detention center in Tecoluca, El Salvador, delivering a speech in front of the inmates. This scene sparked controversy over detainee human rights issues. Photo by AP Yonhap News

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In May 2025, Christy Nomm, Secretary of the Department of Homeland Security, is riding a camel ahead of inspecting the Qal'at Al Bahrain fortress near Manama, Bahrain. /AFP Yonhap News Photo

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Since the beginning of her tenure, she has repeatedly drawn criticism for excessive media appearances, self-promotion, misuse of budgets, and abuse of authority. Early in her term, she was embroiled in controversy for filming a promotional video at a prison in El Salvador, wearing a $60,000 Rolex watch with inmates in the background.

Homeland Security Secretary Kristi Noem appeared at a hearing held at the U.S. Capitol in Washington on March 3, 2026. Photo by AP News Agency

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On March 3, 2026, at a hearing held at the United States Capitol in Washington, Secretary Christi Nomm is being questioned about the luxurious jet's interior bedroom and related matters. / YouTube Capture

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The Coast Guard under the Department of Homeland Security (DHSUnited States Department of Homeland Security (DHS).) signed a contract in October last year to purchase two jets for $172 million (about KRW 250 billion), which also became a source of controversy. At the congressional hearing on March 3, Secretary Noem claimed the official purpose of these jets was for long-distance command and control. However, since they are top-class models (Gulfstream G700) with spacious interiors and luxury amenities, there was criticism that they were essentially luxury private jets for Secretary Noem.

At the same hearing, rumors of an affair between Secretary Noem and her aide, Corey Lewandowski-known as one of her inner circle at DHS-also surfaced. The New York Post reported, "Asked if she had sexual relations with Lewandowski, Secretary Noem called it a 'garbage question' but did not deny it," adding, "Her attitude at the hearing played a decisive role in President Trump's decision to fire her."

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A TV campaign ad for border security, produced by DHS, also stirred controversy. The ad, featuring Secretary Noem in a cowboy hat riding a horse in front of Mount Rushmore and saying, "Enter legally," was criticized for excessively highlighting her personally.

At the hearing, lawmakers focused on the enormous government budget spent on the ad and suspicions that contracts had been funneled to acquaintances. At the time, Secretary Noem explained that the ad was "approved by the President," but President Trump told Reuters in a phone interview that "I had no idea" about it.

John Kennedy, a Republican senator close to President Trump, told reporters after the dismissal that "on the night of the congressional hearing, President Trump was so angry that he called me," adding, "The President was mad as a murder hornet."

He was praised for being so good at his job...
but in the end, the Department of Homeland Security went from being Trump's pride to a burden.

He was the ruthless Christie, but amid numerous controversies, it is evaluated that his false testimony claiming he had President Trump's approval for the ultra-expensive ads was the final blow that led to his dismissal.