"The air cargo system is a complex, multi-faceted network that is vulnerable to several security threats including: potential plots to place explosives aboard aircraft; illegal shipments of hazardous materials; criminal activities such as smuggling and theft; and potential hijackings and sabotage by persons with access to aircraft. Several procedural and technology initiatives have been proposed to enhance air cargo security and deter terrorist and criminal threats which include proposals to: expand the 'known shipper' program; increase cargo inspections; increase physical security of air cargo facilities; increase oversight of air cargo operations; provide security training for cargo workers; and tighten controls over access to aircraft during cargo operations as well as new technologies. The Aviation and Transportation Security Act (ATSA, P.L. 107-71) contains general provisions for cargo screening, inspection, and security measures. Cargo carried in passenger airplanes must be screened or its security otherwise ensured. ATSA also mandated that a security plan for all-cargo operations was to be put in place as soon as possible, but aviation security initiatives to date have primarily focused on enhancing the security of passenger operations."
CRS Report for Congress, RL32022