The Transportation Security Administration (TSA) cannot prove that an overwhelming majority of the behavior indicators it uses to stop terrorists are scientifically valid, according to a new report from the Government Accountability Office (GAO).

In preflight security screenings, the TSA uses 36 types of behavioral detection to try to spot passengers who exhibit behaviors associated with stress or fear.

But the GAO found in their analysis of the TSA's 36 types of behavioral indicators to identify potential terrorists and other threats to airline passenger safety, only eight could be supported by scientific evidence.

The scathing report noted that only three of the 178 sources the TSA used to justify its practices were deemed to be valid. Most of the sources the TSA used were not academic journals, choosing instead to cite news and opinion pieces.

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The GAO said it shared a draft of its findings with the Department of Homeland Security, which responded by saying that “behavior detection has been shown to be a successful tool in preventing individuals from circumventing screening at airports,” according to the office.

In a statement emailed to The Hill, the TSA defended its methods.

“While we respect the opinions of our GAO colleagues, TSA remains steadfast in the effectiveness of behavior detection and committed to training our officers in these widely used techniques," saids TSA spokesperson James Gregory.

Rep. Bennie Thompson (D-Miss.), who requested the study with Rep. Bonnie Watson Coleman (D-N.J.), blasted the TSA after the report.

“After pressing TSA for years to provide scientific justification for its billion dollar behavior detection program, it is ridiculous that TSA provided little more than news articles and opinion pieces,” Thompson said in a statement.

“The thousands of TSA personnel working in this program could be put to better use focusing solely on proven screening activities. It is clear, yet again, that Congress should cut funding for this troubled program, which is known more for racial and ethnic profiling than detecting terrorist activity.”

A GAO analysis in 2013 found that the TSA’s behavior detection methods were lacking. The study recommended cuts to the agency’s funding until it could scientifically validate its techniques.

This story was updated on July 25, 2017 at 9:59 p.m.