US President Donald Trump has fired his embattled Homeland Security Secretary Kristi Noem and announced he would nominate in her place Oklahoma Republican Sen. Markwayne Mullin. Trump made the announcement in a post on Truth Social on Thursday, two days after Noem faced a grilling on Capitol Hill from GOP members as well as Democrats. Trump said Noem had "served us well, and has had numerous and spectacular results," and would instead be made a special envoy for the "The Shield of the Americas,” a new security initiative that he said would focus on the Western Hemisphere. "Thank you @POTUS Trump for appointing me as the Special Envoy for the Shield of the Americas," Noem wrote on X. "@SecRubio and @SecWar are incredible leaders, and I look forward to working with them closely to dis...