National security -- 7 Terrorism -- 3 United States 3 Foreign relations 2 International relations 2 Prevention 2 Security Management 2 more ... Economic development 1 Foreign relations -- 1 Homeland security 1 Infrastructure -- 1 International security 1 Military policy 1 Safety measures 1 Security measures 1 September 11 Terrorist Attacks, 2001 1 Transportation -- 1 War (International law) 1 War on terrorism, 2001- 1 Weapons of mass destruction 1 World politics 1 less ...