" In 2010, passenger flights transported about 3.6 billion pounds of cargo into the United States from foreign locations. According to TSA, the introduction of explosive devices in air cargo shipments is a significant threat, and DHS was mandated to establish a system to screen 100 percent of cargo transported on all passenger aircraft traveling to, from, or within the United States by August 2010. Individuals identified as matches to the No Fly List are generally prohibited from boarding commercial aircraft because it has been determined they pose a threat to civil aviation or national security. GAO was asked to examine (1) TSA actions taken since October 2010 to enhance the security of inbound air cargo transported on both passenger aircraft and all-cargo carriers; and (2) any associated challenges TSA faces. GAO reviewed relevant requirements and documents, interviewed federal officials, and visited three airports based on cargo volume. The visits provided insights, but were not generalizable to the entire industry. This is a public version of a sensitive security report GAO issued in March 2012, which also addressed U.S. Customs and Border Protection's and TSA's use of the No Fly List to secure inbound air cargo. "