Security measures -- Terrorism -- 4 Government policy -- 3 Security measures 3 Computer networks -- 2 Computer security -- 2 Embassy buildings -- 2 more ... National security -- 2 Prevention 2 Prevention -- 2 Administrative agencies -- 1 Aeronautics -- 1 Aeronautics, Commercial -- 1 Air travel -- 1 Airports -- 1 Buildings -- 1 Business -- 1 Business enterprises -- 1 Civil defense 1 Civil defense -- 1 Cyber intelligence (Computer security) -- 1 Defenses 1 Diplomatic and consular service, American -- 1 Economic aspects 1 Effect of terrorism on 1 Embassy takeovers 1 Hacking -- 1 Harbors -- 1 Hijacking of aircraft -- 1 Industries -- 1 less ...