Civil defense -- Terrorism -- 5 Prevention. -- 4 Defenses 3 National security -- 3 War on Terrorism, 2001-2009 2 Armed Forces -- 1 more ... Civil defense 1 Disaster relief -- 1 Emergency management -- 1 Harbors -- 1 History 1 History. -- 1 Internal security -- 1 Law enforcement -- 1 Merchant marine -- 1 Military planning -- 1 National security 1 Organization 1 Police -- 1 Politics and government -- 1 Prevention 1 Security measures 1 Security measures -- 1 less ...