The Transportation Security Administration (TSA) has been conducting a tracking program targeting ordinary Americans in airports since at least 2010, according to new reports. The program, called “Quiet Skies,” used small teams of air marshals to watch and record the actions of thousands of unsuspecting Americans before boarding and aboard flights. According to the reports, all American citizens who enter the United States are automatically considered for inclusion in the program.

The TSA says that the aim of the program is to try to thwart any potential aviation threats. The agency says that Congress is aware of the program and provides “robust” oversight. In response to questions, TSA spokesman James O. Gregory offered more details of the program’s origins and goals.

The agency uses information from the intelligence community and passengers’ previous travel patterns to help choose whom to target under the Quiet Skies program. Once the targets have been chosen, federal marshals use an agency checklist to record the passenger’s behavior. The marshals look for things like how many times the person has been to the bathroom, whether they are fidgeting or perspiring excessively, and whether their appearance matches previous information. Officials have not disclosed whether any terrorist plots have been thwarted because of the program.

The program raises new questions about how much privacy ordinary Americans should have as they travel within the United States. Gregory said the program should not be considered surveillance because the agency does not take actions such as listening to passengers’ calls or following flagged individuals around outside airports. The agency also clearly stated in its statement that individuals are not targeted based on race or nationality.

The TSA, created shortly after the Sept. 11, 2001, terrorist attacks, is tasked with screening more than 2 million passengers a day, on average, at airports across the country. Its track record has been less than stellar. During a secret exercise conducted in 2015, undercover agents were able to get fake bombs past TSA security screeners about 95 percent of the time.