Civil defense -- Terrorism -- 6 National security -- 4 Defenses 3 Prevention. -- 3 Emergency management -- 2 Prevention -- 2 more ... Civil defense 1 Civil rights -- 1 Disaster relief -- 1 Government policy -- 1 Harbors -- 1 Merchant marine -- 1 National security 1 Politics and government -- 1 Prevention 1 Security measures 1 Security measures -- 1 War on Terrorism, 2001-2009 1 less ...