President Donald Trump announced Thursday that he will replace Kristi Noem as secretary of the U.S. Department of Homeland Security in the first major Cabinet change of his second presidential term. Trump said Markwayne Mullin, a Republican senator from Oklahoma, will assume the role later this month.
The president made the announcement in a post on the social media platform Truth Social, saying Mullin would take over leadership of the department at the end of March.
“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,” Trump wrote.
Trump also indicated that Noem will transition to a new diplomatic role as special envoy for “The Shield of Americas,” an initiative described as focusing on cooperation across the Western Hemisphere. In the same post, Trump thanked Noem for her service, stating the former governor “has served us well.”
The leadership change follows months of speculation about Noem’s standing within the administration. While she has long been viewed as a loyal ally of the president, questions about her performance intensified in recent weeks.
Earlier this week, Noem appeared before members of Congress in two separate hearings where she faced criticism, including from some Republican lawmakers. During those appearances, lawmakers raised concerns about a $220 million advertising campaign connected to the Department of Homeland Security that prominently featured Noem.
In addition, the department’s inspector general has asserted that Noem had been hindering certain investigative efforts, a claim that drew additional attention during the congressional hearings.
The Department of Homeland Security did not immediately respond to requests for comment regarding the leadership change or the issues raised during the hearings.
Noem previously served as governor of South Dakota before joining Trump’s Cabinet. During her time in national politics, she has frequently aligned herself with the president and his policy priorities. At one point during Trump’s earlier presidency, she publicly floated the idea of adding Trump’s likeness to Mount Rushmore, the monument located in her home state.
Pressure on Noem’s tenure as homeland security secretary also increased following two fatal incidents in Minneapolis tied to immigration enforcement operations. The deaths occurred amid a surge in enforcement activity in the area.
After the incidents, Noem circulated claims that both individuals killed by immigration officers had been committing acts of domestic terrorism at the time they were shot. Those assertions drew scrutiny as details of the cases continued to emerge.
Mullin, who currently represents Oklahoma in the U.S. Senate, is expected to assume leadership of the department on March 31. His appointment marks the first major personnel change in Trump’s Cabinet since the start of the president’s second term.
The Department of Homeland Security oversees a broad range of federal responsibilities, including border security, immigration enforcement, disaster response, and counterterrorism coordination. Mullin’s confirmation process and transition timeline are expected to draw attention in the coming weeks as the administration reshapes its national security leadership.
