Prevention Terrorism -- Foreign relations 5 Terrorism 3 National security -- 2 September 11 Terrorist Attacks, 2001 2 War on Terrorism, 2001-2009 2 more ... Civil defense 1 Civil defense -- 1 Defenses 1 Economic development 1 Foreign relations -- 1 Globalization 1 Harbors -- 1 Just war doctrine 1 Merchant marine -- 1 Military policy 1 National security 1 Politics & government 1 Politics and government -- 1 Security measures 1 Security measures -- 1 United States 1 less ...