Sean Cairncross was confirmed as the National Cyber Director by the United States Senate on August 2, 2025, and joined the White House as President Trump’s principal advisor on national cybersecurity policy and strategy. Before leading the Office of the National Cyber Director, Mr. Cairncross served as the Chief Operating Officer for the Republican National Committee, overseeing operations during both the 2024 and 2016 presidential cycles. In 2019, he was appointed by President Trump and confirmed by the U.S. Senate as the Chief Executive Officer of the Millennium Challenge Corporation. Prior to this appointment, he served as Deputy Assistant to the President and Senior Advisor to the White House Chief of Staff. He has also served as Deputy Executive Director and General Counsel to the National Republican Senatorial Committee under Senator John Cornyn (R-TX) from 2009 to 2013 and as RNC Chief Counsel from 2007 to 2009.