Subversive activities History 87 Politics and government 36 Communism 24 Internal security 20 Spies 19 Espionage 16 more ... Terrorism 16 Foreign relations 15 Cold War 14 Espionage, Soviet 13 Intelligence service 11 World War, 1939-1945 11 Insurgency 10 Political aspects 10 Anti-communist movements 9 Officials and employees 9 Relations 9 Prevention 8 Secret service 8 Social aspects 8 Espionage, American 7 National security 7 Internet 5 Political activists 5 Trials (Political crimes and offenses) 5 Communists 4 Counterinsurgency 4 Guerrilla warfare 4 Historia 4 less ...