(George Frey/Reuters) (George Frey/Reuters)

A new report casts strong doubt on the effectiveness of one of the government’s main tools for detecting potential terrorists before they board airplanes: behavior detection efforts by the Transportation Security Administration.

Stephen M. Lord, a Government Accountability Office official, told a House Homeland Security subcommittee hearing Thursday that there is no solid evidence that the TSA techniques are effective.

“Until TSA can provide scientifically validated evidence demonstrating that behavioral indicators can be used to identify passengers who may pose a threat to aviation security, the agency risks funding activities that have not been determined to be effective,” according to a GAO report.

TSA Administrator John S. Pistole defended the work of agency behavior detection officers (BDOs), telling the panel they “provide a crucial layer of security. “