Air cargo security has come far since the Sept. 11, 2001, terrorist attacks turned the tools of transportation and trade into weapons of mass destruction. Until 9/11, the lone form of security in the U.S. was an unregulated program in which airlines vetted shippers to ensure they and their products were legitimate. The so-called known shipper program was enhanced following 9/11 and remains in effect. Today, a shipper must be known to the carrier in order to load cargo aboard a passenger flight...
https://www.freightwaves.com/news/for-air-cargo-security-the-past-is-prologue