Customs and Border Protection is estimating it will take between three and five years to complete its deployment biometric entry and exit solutions at U.S. airports, a delay from prior expectations.

Those estimates represent at least a two-year delay from prior expectations made by then Acting CBP Commissioner Kevin McAleenan in late 2017 after the Trump administration sought to expedite the rollout of facial recognition technology to airports to help verify the departure of foreign nationals from the U.S. on international flights in accordance with their visa terms.

CBP on Thursday rescinded a 2008 Notice of Proposed Rulemaking (NPRM) related to its biometric exit program and replaced it with a new proposal that expands the number of airports where the technology can be deployed and allows the agency to expand pilot evaluations at land, air and seaports and move to operational deployments, which is something it has already been doing. The new NPRM also removes some limitations on the legal framework for requiring aliens to provide biometrics when entering and departing the U.S.

Current regulations limit CBP to testing and evaluating biometric entry and exit systems under pilot programs at land ports and up to 15 air and seaports. However, as of September 2020, facial recognition capabilities were deployed at 20 airports, including 21 terminals, eight land ports of entry—seven on the southwest border and one on the northern border-and at seven seaport locations for cruises.

For biometric exit at airports, either airlines or airports purchase the cameras to take live photos of passengers at the departure gate for matching against a limited database of photos maintained by CBP in its Traveler Verification System. Use of the facial comparison technology eliminates the need for travelers to present a boarding pass and passport at the gate. U.S. citizens can opt out of having their photos taken at the gate but then must present their travel documents to the gate agent for review.

“For land and sea ports of entry and private aircraft, CBP plans to continue to test and refine biometric exit strategies with the ultimate goal of implementing a comprehensive biometric entry-exit system nationwide,” says the November 19 proposed rulemaking. It adds that if the proposal is adopted, it will “continue to expand testing as necessary.”

The biometric entry-exit program was mandated by Congress more than 20 years ago. Entry processes for foreign nationals arriving to the U.S. have included fingerprint capture and matching for more than 15 years but CBP is introducing facial recognition to these processes.

The use of biometric comparison technology also helps ensure that an individual presenting a government-issued travel document is the same person that was issued the document, which mitigates fraud and abuse.

CBP says that within several weeks of implementing facial recognition technology for international arrivals at Washington Dulles International Airport in Northern Virginia two impostors were identified trying to enter the U.S. using someone else’s passport. The technology has also identified at least 138 impostors attempting to enter the U.S. with another person’s travel documents at two ports of entry in Arizona.

“While it is difficult to quantify the number of instances in which such fraud has occurred but not been identified by CBP because facial recognition technology is not broadly used at present, DHS expects that the implementation of this rule would greatly enhance DHS’s ability to identify more of these impostors,” CBP says.

The comment period for the proposed rule closes on Dec. 21.