National security -- Politics and government -- 4 Terrorism -- 3 Civil defense 1 Civil defense -- 1 Civil rights -- 1 Defenses 1 more ... Defenses -- 1 Economic aspects 1 Foreign relations 1 Foreign relations -- 1 Government policy -- 1 Harbors -- 1 Merchant marine -- 1 Military policy 1 National security 1 Politics and government 1 Prevention 1 Prevention -- 1 Prevention. -- 1 Security measures 1 Security measures -- 1 United States -- 1 War on Terrorism, 2001-2009 1 War on terrorism, 2001- 1 World politics -- 1 less ...