President Donald Trump announced Thursday that Homeland Security Secretary Kristi Noem is leaving the department and being replaced by Sen. Markwayne Mullin, R-Okla.
“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 in a post on Truth Social.
He added that Noem “has served us well,” and she will step into a new role called “Envoy for The Shield of the Americas.”
The leadership change comes as DHS remains shut down amid a congressional funding standoff tied to immigration policy disputes. Lawmakers remain divided over whether a DHS funding bill should include new provisions governing federal immigration enforcement operations.
Noem also faced criticism from lawmakers during congressional hearings this week over the administration’s immigration enforcement tactics.
The transition also arrives during a period of leadership turnover within the Cybersecurity and Infrastructure Security Agency (CISA), which operates under DHS and plays a central role in federal cybersecurity and infrastructure protection efforts.
Last week, Madhu Gottumukkala departed his role as CISA’s acting director to take another position within DHS. Nick Andersen, previously the agency’s executive director for cybersecurity, is now serving as acting director.
Separately, CISA Chief Information Officer Bob Costello announced on Tuesday that he will leave the agency at the end of this week.
Mullin’s nomination to lead DHS will require Senate confirmation.