National security -- Terrorism -- 12 Prevention. -- 9 Prevention -- 4 Civil defense -- 3 Civil rights -- 3 Government policy -- 2 more ... Intelligence service -- 2 Law enforcement -- 2 Air power -- 1 Emergency management -- 1 Evaluation. -- 1 Foreign relations 1 Foreign relations -- 1 Information warfare -- 1 Internal security -- 1 International cooperation 1 Law and legislation -- 1 Military policy 1 Nuclear weapons information -- 1 Planning. -- 1 Politics and government 1 Politics and government -- 1 Security measures 1 September 11 Terrorist Attacks, 2001 1 Terrorism 1 Terrorists -- 1 War on Terrorism, 2001-2009 1 less ...