US President Donald Trump has announced that Senator Markwayne Mullin of Oklahoma will become the next Secretary of the United States Department of Homeland Security (DHS), with the appointment set to take effect on March 31, 2026.

Mullin is replacing Homeland Security Secretary Kristi Noem. In his Truth Social post announcing Noem’s replacement, Trump praised her for her tenure leading the Department of Homeland Security, highlighting what he described as her strong performance on border security. Noem has “served us well, and has had numerous and spectacular results (especially on the Border!)”

Trump emphasized Mullin’s political loyalty and alignment with his policy agenda, describing him as a supporter of the “America First” platform. “Serving 10 years in the United States House of Representatives, and three in the Senate, Markwayne has done a tremendous job representing the wonderful people of Oklahoma,” Trump said.

He also referenced his own electoral victories in the state, noting that he won all 77 counties in Oklahoma during the presidential elections of 2016, 2020, and 2024.

Trump suggested that Mullin’s political experience and close connection with voters in the state make him well positioned to take on the leadership role at DHS.

Trump pointed to this background as evidence of Mullin’s determination and resilience.“A MAGA Warrior, and former undefeated professional MMA fighter, Markwayne truly gets along well with people, and knows the Wisdom and Courage required to Advance our America First Agenda,” Trump said in the statement.

Trump expressed confidence that Mullin’s leadership style and experience would help drive forward his administration’s priorities within the department. He said the Oklahoma Senator possesses the qualities needed to lead the agency and continue advancing the administration’s security 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. Markwayne will make a spectacular Secretary of Homeland Security. Thank you for your attention to this matter!”
Donald Trump

Trump made the announcement two days after Noem faced a grilling on Capitol Hill from GOP members as well as Democrats.

Noem is the first Cabinet secretary to leave during Trump’s second term. Noem’s departure caps a tumultuous tenure overseeing immigration enforcement tactics that have been met with protests and lawsuits.

Noem has faced waves of criticism as she’s overseen Trump’s immigration crackdown, especially since the shooting deaths of two protesters in Minneapolis at the hands of immigration enforcement officers.

The former South Dakota Governor was also criticized over the way her department has spent billions of dollars allocated to it by Congress.

Frustrations over Noem’s execution of the Republican President’s hard-line immigration agenda — particularly her leadership after the shooting deaths of the two UScitizens in Minneapolis — as well as her handling of disaster response, paved the way for her downfall.

She faced blistering criticism from Democrats, and some Republicans, in Congress hearings this week over those issues and others.

Aside from immigration, Noem also faced criticism — including from Republicans — over the pace of emergency funding approved through the Federal Emergency Management Agency and for the Trump administration’s response to disasters.

Mullin would need to be confirmed by the Senate, but under a federal law governing executive branch vacancies, he would be allowed to serve as an acting Homeland Security secretary as long as his nomination is formally pending.

Trump Makes Noem Envoy For New Security Initiative

Meanwhile, Trump said in his post that he’ll make Kristi Noem a “Special Envoy for The Shield of the Americas,” a new security initiative that he said would focus on the Western Hemisphere.

He disclosed that the initiative will be announced on Saturday in Doral, Florida.

Noem’s new assignment as Special Envoy for “The Shield of the Americas” suggests a broader regional approach to security challenges in the Western Hemisphere.

While full details of the initiative have yet to be announced, Trump indicated that the program will focus on strengthening security cooperation among countries in the region.