Espionage History 66 Intelligence service 47 Spies 27 Secret service 17 Military intelligence 10 Foreign relations 9 more ... Cold War 8 International relations 7 National security 7 World War, 1939-1945 7 Electronic surveillance 6 Communism 5 Espionage, American 5 Politics and government 5 Security measures 5 Subversive activities 5 Histoire 4 Prevention 4 Social aspects 4 Arab-Israeli conflict 3 Catholics 3 Confidential communications 3 Diplomatic relations 3 Electronic intelligence 3 Equipment and supplies 3 Espionage, Soviet 3 Fedayeen 3 Invisible inks 3 Moral and ethical aspects 3 less ...