Throughout his career as director of the FBI, J. Edgar Hoover documented his concerns about Communism, subversion, and anti-American activities in the United States. These concerns are reflected in testimony he gave before the House Un-American Activities Committee as well as in reams of memoranda and letters he issued to the FBI’s deputy director, agents in charge of FBI field offices, and others. An overriding theme is how the nation and the FBI should respond to these threats, whether real or imagined. In his June 29, 1965, Memo on the Leak of Vietnam War Information, he summarizes his conversation with President Lyndon B. Johnson about a leak of information concerning the acceleration of war in Vietnam.