Bossert, a former deputy national security adviser to President George W. Bush, had overseen the Trump administration's response to the Hurricane Maria disaster in Puerto Rico, as well as cybersecurity policy. An official said John Bolton, who started his new role on Monday, urged Bossert's departure. Bossert ran the administration’s work on cyber security issues and was considered a key voice for responding more aggressively to destructive cyber attacks launched by hostile adversaries, including Russia, Iran and North Korea. Bossert for the past 7½ years has headed CDS Consulting, a private risk management firm. Since 2013, Bossert also has served as a senior fellow at the think tank Atlantic Council's Cyber Statecraft Initiative. Mr. Bossert earned his law degree from George Washington University and his Bachelor’s Degree from the University of Pittsburgh. He was born and raised in Quakertown, Pennsylvania.