Oklahoma Gov. Kevin Stitt (R) appointed Armstrong to the Senate seat vacated by Sen. Markwayne Mullin (R), who was confirmed as homeland security secretary Monday.

Mullin sworn in as DHS Secretary, as Alan Armstrong fills U.S. Senate seat Tuesday, Markwayne Mullin was sworn in as the new Secretary of the Department of Homeland Security. Energy executive Alan ...

Markwayne Mullin was sworn in as secretary of the Department of Homeland Security on Tuesday, taking the oath of office at ...