Thomas P. Bossert (born March 25, 1975)[1] is an American lawyer and former Homeland Security Advisor to U.S. President Donald Trump.

[3] Immediately before, he was a fellow at the Atlantic Council and prior to that he served as Deputy Homeland Security Advisor to President George W. Bush.

Prior to that, Bossert held positions in the Federal Emergency Management Agency, the Small Business Administration, the Office of the Independent Counsel, and the House of Representatives.

[11] Bossert resigned on April 8, 2018, the day after John R. Bolton, the newly appointed National Security Advisor, started his tenure.

[13] On December 16, 2020, the New York Times published an opinion piece by Bossert warning that U.S. networks had been seriously compromised by Russia and had been for months.