The Department of Homeland Security has pared the number of Federal Air Marshals - plain-clothed officers whose job is to protect aircraft from terrorists - during the past three years, according to an internal email obtained by CNN.
Budget cuts have "led to ... a reduction in FAMs (Federal Air Marshals) through attrition," the email said.
The exact number of marshals is secret, and the Homeland Security Department on Tuesday declined to say how positions have been eliminated. Nor would it say what percentage of marshals positions were cut.
But critics, including some air marshals, say the secrecy allows the government to cut the workforce without acknowledging it, as happened in the years leading up to the September 11, 2001, terrorist attacks.
At that time, fewer than 40 people were in the air marshal workforce and none were on the hijacked planes.
Following the attacks, DHS assumed responsibility for the program and ramped up its ranks on domestic and international flights serving the United States.
Their numbers grew exponentially and although the figure is confidential, the agency two years ago negotiated pay disputes with some 3,500 air marshals - a number believed to represent the bulk of the workforce.
Air Marshal Director Robert Bray said in an e-mail, sent Friday, that the agency's budget has been cut from $966 million to $805 million in the past three years. He outlined plans to close six of the agency's 26 field offices in coming years.
San Diego and Tampa will close by the end of 2014, followed by Pittsburgh and Phoenix, by June 2015, and Cleveland and Cincinnati by June 2016, the email says.
In addition, the agency has frozen hiring at three other offices: Las Vegas, Seattle, and Denver, the email says.
Existing personnel will be reassigned to other offices, and the closures "will not adversely impact our ability to maintain coverage onboard flights at the corresponding airports," Bray wrote.
Jon Adler, president of the Federal Law Enforcement Officers Association, noted the drop-off.
"There's definitely been attrition, but not from the natural progression of a 20-year retirement," said
Adler, president of the Federal Law Enforcement Officers Association, which includes air marshals. "'Attrition' is really a euphemism for 'exodus,'" Adler said.
Air marshals complain the agency suffered from mismanagement, particularly in the early years of the program.
Two years ago, the DHS Inspector General concluded that agency supervisors did not engage in "widespread" discrimination, but that air marshals shared a widespread "perception" that they were being mistreated.
It also said that investigators "heard too many negative and conflicting accounts" of misconduct to dismiss them.
"Federal air marshals repeatedly portrayed their supervisors as vindictive, aggressive, and guilty of favoritism," the report said. "There is a great deal of tension, mistrust and dislike."
In his email, Bray said the consolidation of field offices is being done after considering mission scheduling, current threat reporting and trends in airline scheduling.
But Adler said he believes DHS is counting on the consolidation of field offices to further thin the ranks.
"There has to be a realistic expectation that the numbers are going to decrease," he said.
Mike Karn, president of the Coalition of Airline Pilots Associations, said it was not wise to cut those positions.
"Diminishing any level of security that we have out there right now concerns me," Karn said.