The senior US official told ABC News that the “dry run” involved a carton of household goods including books, religious literature, and a computer disk, but no explosives, shipped from Yemen to an address in Chicago by “someone with ties to al Qaeda in the Arabian Peninsula.”

Another person briefed on the incident said it is now believed the terrorists sent the package “so they could track how long it took and whether there would be any problems for the package getting through the system.”