Security measures Terrorism -- Prevention 6 Aeronautics, Commercial -- 4 Prevention. -- 3 War on Terrorism, 2001-2009 3 Airports -- 2 more ... Evaluation. -- 2 Government policy -- 2 Hijacking of aircraft -- 2 Merchant marine -- 2 National security -- 2 Security measures -- 2 Air power -- 1 Boats and boating -- 1 Civil defense 1 Civil defense -- 1 Defenses 1 Freight and freightage -- 1 Harbors -- 1 Hijacking of ships -- 1 Information warfare -- 1 Military policy 1 National security 1 Passenger traffic 1 Pirates 1 Politics and government -- 1 Safety measures 1 Shipping -- 1 Surface-to-air missiles 1 less ...