President Donald Trump on Thursday announced that Department of Homeland Security Secretary Kristi Noem would leave her post at the end of the month and that he had tapped Sen. Markwayne Mullin, R-Okla., as her replacement.

The announcement came shortly after reports of Trump's plans to fire Noem went public. Trump had reportedly expressed frustration with Noem for telling Congress he signed off on a $200 million ad campaign featuring herself that he allegedly considered too self-promotional.

"I am pleased to announce that the Highly Respected United States Senator from the Great State of Oklahoma, Markwayne Mullin, will become the United States Secretary of Homeland Security (DHS), effective March 31, 2026," he posted on Truth Social. "The current Secretary, Kristi Noem, who has served us well, and has had numerous and spectacular results (especially on the Border!), will be moving to be Special Envoy for The Shield of the Americas, our new Security Initiative in the Western Hemisphere we are announcing on Saturday in Doral, Florida. I thank Kristi for her service at “Homeland.”

Trump called Mullin "[a] MAGA Warrior, and former undefeated professional MMA fighter," saying, "Markwayne truly gets along well with people, and knows the Wisdom and Courage required to Advance our America First Agenda."

"Markwayne will work tirelessly to Keep our Border Secure, Stop Migrant Crime, Murderers, and other Criminals from illegally entering our Country, End the Scourge of Illegal Drugs and, MAKE AMERICA SAFE AGAIN," he added. "Markwayne will make a spectacular Secretary of Homeland Security. Thank you for your attention to this matter!"

Noem's ouster marks the first major Cabinet shakeup since National Security Advisor Mike Waltz was moved to the U.N. Ambassador post last year. That development stemmed from the accidental inclusion of a reporter in a groupchat of Cabinet officials in which they planned strikes on Yemen's Houthi rebels.

Ben Whedon is the Chief Political Correspondent at Just the News. Follow him on X.