Washington, 6 March 2026 (dpa/MIA) - US President Donald Trump has dismissed his controversial Homeland Security Secretary Kristi Noem, he posted on his platform Truth Social on Thursday.

Oklahoma Senator Markwayne Mullin is to lead the department responsible for immigration and border protection agencies effective March 31, Trump wrote.

"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," he said.

"I thank Kristi for her service at 'Homeland,'" Trump added.

Noem is thus the first minister from the current US administration to step down. In a statement, she thanked Trump for appointing her as special envoy, calling the Western Hemisphere "absolutely critical for U.S. security."

"We have made historic accomplishments at the Department of Homeland Security to make America safe again," she added in a statement shared on social media platform X.

Mullin, who is set to succeed Noem, was a member of the US House of Representatives for 10 years and a senator for three years, according to Trump. "Markwayne will make a spectacular Secretary of Homeland Security," the US president said.

He is to focus on border security and tackle crime by migrants without residence permits.

Once Trump's preferred candidate

Noem, once Trump's preferred candidate for the position, was previously the governor of South Dakota and made a name for herself as a staunch supporter of Trump. Even before her appointment as secretary, she described the situation at the US-Mexico southern border as a "war zone."

At one point considered as Trump's vice-presidential candidate, her memoirs brought her negative headlines: In them, Noem described how she shot her young dog, Cricket, because it was not suitable as a hunting dog. She later explained that this demonstrated her willingness to make tough decisions.

Noem was under pressure

In a Senate hearing, the 54-year-old was recently questioned about deaths during operations by immigration and border protection agencies targeting migrants and the tactics of her department. The sometimes brutal operations led to nationwide protests. Critics accuse the administration and Noem of violating civil rights.

As recently as the end of January, Trump demonstratively stood by Noem, saying she was doing "a very good job" after federal officers fatally shot two US citizens during clashes with residents.

This was followed by a budget dispute over the direction and funding of immigration policy: While Republicans are calling for even tougher measures, Democrats criticize the expansion of powers and demand stronger congressional oversight and transparency in exchange for funding.

Multimillion campaign led to criticism

During the hearing, Noem repeatedly stressed that her department's measures served national security and were based on legal grounds. She was also asked if she wanted to retract her previous statements that the killed US citizens should be considered domestic terrorists.

The description came in for strong criticism later when compared to video footage and local reports. Noem stated that she relied on reports from on-site forces and explicitly refused to retract her statements or apologize.

What ultimately proved to be Noem's downfall was a multimillion-dollar advertising campaign to deter illegal migration.

A Republican senator noted that the campaign seemed more for self-promotion than effective enforcement. Noem claimed that the budget for it had been approved by Trump, to which the senator responded that he could not imagine that, as it would put Trump in an extremely uncomfortable position.

Trump himself later said he had not agreed. Overall, the hearing showed that concerns about Noem's leadership behaviour are now bipartisan.

Photo: EPA