National security -- Terrorism -- Government policy -- 9 Prevention. -- 9 Prevention -- 8 Civil defense -- 5 Civil rights -- 4 more ... War on Terrorism, 2001-2009 4 History -- 3 Intelligence service -- 3 Politics and government -- 3 Defenses 2 Emergency management -- 2 Foreign relations 2 Foreign relations -- 2 Law enforcement -- 2 Security measures 2 September 11 Terrorist Attacks, 2001 2 Air power -- 1 Civil defense 1 Cross- cultural studies 1 Evaluation. -- 1 Governmental investigations -- 1 Harbors -- 1 Information warfare -- 1 Internal security -- 1 International cooperation 1 Law and legislation -- 1 Merchant marine -- 1 Military policy 1 less ...