President Donald Trump will nominate Kirstjen Nielsen, who as top aide to his White House chief of staff has sought to instill order in Trump¡¯s team, to lead the U.S. Department of Homeland Security, the White House said in a statement on Wednesday.

If confirmed by the Senate, Nielsen would take the reins at a sprawling department with more than 240,000 employees that is responsible for U.S. border and airport security, immigration policy, disaster response, refugee admissions and other matters.

Nielsen, 45, is a cybersecurity expert with a considerable resume in homeland security that includes work at the department¡¯s Transportation Security Administration and on former Republican President George W. Bush¡¯s White House Homeland Security Council.