National security -- 7 Terrorism -- 5 Politics and government -- 3 Prevention. -- 3 Defenses 2 Foreign relations -- 2 Military policy 2 more ... Security measures 2 War on Terrorism, 2001-2009 2 Air power -- 1 Civil defense 1 Civil defense -- 1 Foreign relations 1 Government policy -- 1 Harbors -- 1 Information warfare -- 1 Intelligence service -- 1 Merchant marine -- 1 National security 1 Nuclear weapons information -- 1 Planning. -- 1 Politics and government 1 Prevention 1 Relations -- 1 Security measures -- 1 World politics -- 1 less ...