A 40-year veteran of the U.S. counterterrorism community, Sheehan served as a top official for the State Department, the Pentagon, and the New York Police Department. As a military officer on the National Security Council staff for Presidents George H.W. Bush and Bill Clinton, he urged officials to place greater priority on the growing threat of militant Islamist groups, especially al-Qaida.
Later in his career, Sheehan focused on non-Islamist challenges to American peace and security. He warned that overreacting to terrorist threats had adverse consequences—including stoking Islamophobia that couldalienate Muslim-American communities, making them less likely to provide tips that had helped thwart and disrupt numerous plots.