(CNN) —  

A government watchdog agency says the Transportation Safety Administration is deficient in its oversight of airport perimeter security – and it could create dangerous vulnerability for the entire U.S. commercial aviation system.

According to a report issued Tuesday by the Government Accountability Office, TSA has failed to update its recommendations to reflect new potential threats. While airports have the day-to-day responsibility of securing their perimeters – as well as all airport access points – TSA is responsible for setting minimum standards for airports to follow.

“TSA has not updated this assessment to reflect changes in the airport security risk environment, such as TSA’s subsequent determination of risk from the insider threat – the potential of rogue aviation workers exploiting their credentials, access and knowledge of security procedures throughout the airport for personal gain or to inflict damage,” the report said.

TSA data shows from 2009-2015 there was on average 2,500 security breaches every year involving the airport perimeter and airport access points – and it appears the number of security breaches is trending upward.

TSA is collecting the data on what’s happening across the country, but it’s failing to analyze the data in an effective way, according to the GAO.

A GAO official told CNN that means the agency could be missing security trends and an opportunity to change or enhance requirements for airport perimeter security.

A TSA spokesman, who declined to be named, said the agency is working with stakeholders to “mitigate risks” and the agency is planning on implementing all GAO recommendations.

“Within the past year, TSA has taken a number of concrete steps to enhance airport security in light of evolving threats, including most recently issuing updated guidelines in February 2015 to further enhance the screening of aviation workers in the secure area of airports,” the spokesman told CNN.

TSA analyzed security breaches at large major airports but overall only did that type of analysis at 19% of the nations 440 airports from fiscal year 2009-2015. Often left out were the small- and medium-sized airports, but GAO found since 2009, more than 1,670 security breaches happened at those same airports the TSA failed to analyze.

The GAO report says the agency must do a better job of looking at the vulnerabilities of airport security nationwide. If not, it could create a vulnerability that threatens the entire U.S. aviation system. For example, if a security breach allows an explosive to be smuggled onto an aircraft at a smaller airport and that aircraft flies to a larger airport, the entire system is at risk.

The audit reminds the agency airport security is “a system of interdependent airport hubs and spokes in which the security of all is affected by the security of the weakest one.”

TSA has said it does not have enough resources to assess security breaches at all U.S. airports, but the GAO report said the agency should do better at finding ways to improve security nonetheless.

“Other approaches, such as providing all commercial airports with a self-vulnerability assessment tool, may allow TSA to assess vulnerability at airports system-wide,” it said.

The audit said the lack of a more thorough analysis means TSA doesn’t truly understand the day-to-day threats at airports nationwide and in turn does not know what steps it needs to take to improve security.

Both the Department of Homeland Security and the FBI have identified the insider threat as the most concerning and pressing threat facing aviation.

Members of Congress requested the investigation after several recent incidents where individuals gained access to secure parts of commercial airports and stowing away onboard commercial aircraft. There have also been incidents of airport workers using their credentials to smuggle weapons and drugs into restricted areas of the airport and onto passenger planes.

In April 2014, a 15-year-old boy allegedly climbed a perimeter fence at San Jose’s Mineta International Airport in California and stowed away in the wheel well of a plane flying to Hawaii. In December 2014, a baggage handler at Atlanta’s Hartsfield-Jackson International Airport in Georgia allegedly used his airport-issued credentials to repeatedly smuggle loaded and unloaded firearms into the passenger boarding area for hand-off to an accomplice, who carried the firearms onto an airplane bound for New York.

As the investigation into what brought down EgyptAir flight 804 continues, the possibility of an insider threat remains on the table.

Members of Congress who requested the audit said the deficiencies highlighted regarding TSA oversight becomes a much bigger issue.

“The intense scrutiny placed at checkpoints in airports, but not on the perimeter, is the equivalent of locking your home’s doors while leaving your windows wide open,” said Rep. William Keating, D-Massachusetts. “The GAO found that in many instances, the windows are open at our airports.”