President Donald Trump announced Thursday that he is removing Kristi Noem from her role as Secretary of the Department of Homeland Security, replacing her with Republican Senator Markwayne Mullin of Oklahoma. The transition is expected to take effect on March 31 and represents the first major cabinet shakeup of Trump’s second presidential term.

In a message posted on Truth Social, Trump praised Noem’s work on border security, stating that she had delivered “numerous and spectacular results.” However, the decision comes after weeks of political pressure tied to controversies surrounding her leadership of the department.

Noem, a former governor of South Dakota and longtime Trump ally, had become one of the most visible figures behind the administration’s immigration enforcement strategy. The Department of Homeland Security oversees Immigration and Customs Enforcement (ICE), Border Patrol and several other agencies that have played a central role in Trump’s mass deportation policy.

Her tenure took a dramatic turn after two U.S. citizens, Renee Good and Alex Pretti, were killed in Minneapolis during operations involving federal immigration agents. Noem publicly described both individuals as “domestic terrorists,” a characterization that was quickly challenged by civil liberties groups and lawmakers who said the evidence did not support the claim. The incidents triggered investigations and calls for accountability from Democrats and some Republicans, who questioned the department’s conduct and leadership.

At the same time, reports surfaced about an alleged personal relationship between Noem and Corey Lewandowski, a former Trump campaign manager who served as a senior adviser within the department. According to reporting by the Wall Street Journal, the relationship and internal management tensions contributed to an increasingly unstable atmosphere at DHS.

Questions also emerged about spending decisions inside the department, including approximately $220 million awarded to a firm linked to Noem’s former spokesperson to produce advertising campaigns prominently featuring the secretary. The growing scrutiny placed the department under unusual bipartisan pressure. Senator Thom Tillis of North Carolina threatened to block Senate business if DHS did not answer oversight questions, while Senator John Kennedy of Louisiana publicly questioned the advertising contracts during congressional hearings.

Despite the controversies, Trump did not criticize Noem in his announcement. Instead, he said she would take on a new role as special envoy for what he called the “Shield of the Americas,” a security initiative that the administration plans to unveil in the coming days.The appointment of Senator Mullin suggests the White House is seeking to reset leadership at a department that remains central to Trump’s political agenda.

For an administration that has made immigration enforcement one of its defining policies, the leadership change signals both the political sensitivity of the issue and the high stakes surrounding the agencies tasked with carrying it out.