North Atlantic Treaty Organization 35 History 33 Defenses 26 Military policy 25 World War, 1939-1945 19 Armed Forces 18 Security, International 18 National security 16 Foreign relations 15 World politics 13 Campaigns 12 Congresses 11 Naval operations 9 Politics and government 9 North Atlantic Treaty Organization (NATO) 8 Atlantic Ocean 7 Europe 7 Submarine 7 Military relations 6 Strategic aspects 6 North Atlantic treaty organization 5 20th century 4 Aerial operations 4 Air forces 4 International relations 4 Membership 4 Military history, Modern 4 Naval operations, American 4 Nuclear warfare 4 Shipwrecks 4