Security measures Terrorism -- 3 War on Terrorism, 2001-2009 Aeronautics, Commercial -- 2 Evaluation. -- 2 Government policy -- 2 Prevention. -- 2 more ... Civil defense 1 Civil defense -- 1 Defenses 1 Harbors -- 1 Merchant marine -- 1 National security 1 National security -- 1 Politics and government -- 1 Prevention 1 Security measures -- 1 less ...