Subversive activities History 31 Communism 12 Politics and government 12 Anti-communist movements 7 Internal security 7 Insurgency 5 more ... Spies 5 Terrorism 5 Espionage, Soviet 4 Human rights 4 National security 4 Political aspects 4 Relations 4 Cold War 3 Espionage 3 Guerrillas 3 Prevention 3 Radicalism 3 Social aspects 3 World War, 1939-1945 3 Communists 2 Counterinsurgency 2 Economic conditions 2 Government, Resistance to 2 Hysteria (Social psychology) 2 Intelligence service 2 Librarians 2 Officials and employees 2 Oppression (Psychology) 2 less ...