History Intelligence service Secret service 42 Espionage 38 Foreign relations 35 Cold War 34 Politics and government 33 more ... Military intelligence 32 Spies 19 World War, 1939-1945 19 Intelligence officers 15 Political aspects 14 Internal security 13 National security 12 Espionage, American 8 Electronic surveillance 7 Espionage, British 7 Officials and employees 7 Presidents 7 Political activity 6 Terrorism 6 Colonies 5 History and criticism 5 Police 5 Prevention 5 Social aspects 5 Corrupt practices 4 Espionage, Soviet 4 Moral and ethical aspects 4 Security, International 4 less ...