U.S. Immigration and Customs Enforcement does not know exactly how many noncitizens who served in the American military it has deported since 2013, according to a new report released by a federal watchdog.

The Government Accountability Office said Thursday that ICE failed to consistently follow its own policies when it came to deporting veterans over the past five years. ICE has policies that mandate the agency give special consideration to veterans in light of their service. But the watchdog noted that because the agency “did not consistently adhere to these policies, some veterans who were removed may not have received the level of review and approval that ICE has determined is appropriate.”

“We found ICE did not consistently follow these policies from 2013-2018,” the watchdog wrote in the report. “ICE also does not maintain complete electronic data on these veterans. As a result, ICE does not know how many veterans have been placed in removal proceedings or removed.”

More than 44,000 noncitizens enlisted in the military between 2013 and 2018, according to Pentagon data. Many of those service members are entitled to apply for American citizenship under the Immigration and Nationality Act, but ICE has the authority to deport veterans who have not obtained citizenship and are in violation of immigration laws or who commit certain crimes.

In a statement to CNN, ICE defended its actions, saying it respected the “service and sacrifice of those in military service” and that the agency took “very deliberate” action when it came to deportation proceedings.

“Any action taken by ICE that may result in the removal of an individual with military service must be authorized by the senior leadership in a field office, following an evaluation by local counsel,” the agency told the outlet.

The report came after Reps. Mark Takano (D-Calif.) and Juan Vargas (D-Calif.) asked GAO to review ICE’s veteran deportation policies. In a letter on Thursday, Takano pointed to several “breakdowns” in agency policy that occurred at “every level where a potentially removable veteran is involved.” The lawmaker said he was “deeply alarmed” that the agency was unable to quantify just how many people had been deported.

“ICE has a responsibility to ensure that its internal policies are being fully executed and that its staff are educated on these existing policies,” Takano wrote.

Vargas told CNN later Thursday that the report reveals “obvious instances of mismanagement” that resulted in many deportations.

“Our government is failing our immigrant veterans ― men and women who have dutifully served our nation,” Vargas told the outlet.

GAO has recommended ICE take action to address the lapse in implementing its own policies. Both Takano and Vargas have also asked Mark Morgan, the agency’s acting director, to clarify ICE’s procedures when it comes to former service members.