By Brittney Melton Good morning. You're reading the Up First newsletter. Subscribe here to get it delivered to your inbox, and listen to the Up First podcast for all the news you need to start your day. President Trump has fired Homeland Security Secretary Kristi Noem and named Sen. Markwayne Mullin of Oklahoma as his choice to replace her. On social media, Trump said Noem would move to a role as "Special Envoy for The Shield of the Americas," a new security initiative he said the administration would announce on Saturday. Mullin, a fairly new face in the Senate, has established himself as a close ally of the president. The Senate will have to confirm Mullin for the DHS role before he can start. Here's what you need to know about Trump's pick. Homeland Security Secretary Kristi Noem attends a meeting in the Oval Office on Nov. 17, 2025.…