WASHINGTON, Mar 6 – Sooner or later, advisers in President Donald Trump’s orbit all come to learn the same unwritten rule: no-one can outshine the boss.Kristi Noem, the secretary of the Department of Homeland Security, became the latest reminder of that on Thursday when Trump announced he was removing her as the face of the administration’s crackdown on immigration.Noem will be replaced by Oklahoma Senator Markwayne Mullin at the end of the month, Trump said in a post on Truth Social. The US Senate will have to confirm him in the post.The president said Noem would move to a new job as special envoy for a new US security initiative in the Western hemisphere called the Shield of the Americas.“I thank Kristi for her service at ‘Homeland,'” Trump said.It ends Noem’s controversial tenure at the top of the department, which is tasked with carrying out the president’s sweeping immigration agenda.Noem was one of the administration’s brightest stars when she stepped into the role last year after Trump returned to the White House. She immediately gained attention for joining immigration raids, often appearing in a bulletproof vest alongside field agents carrying out enforcement actions.She was a vocal advocate of Trump’s deportation drive, and touted policies that effectively closed the US-Mexico border. She also took the message abroad, in one instance visiting a maximum-security prison in El Salvador that took in some migrants deported from the US.