Thompson appeared in federal court in Washington on Wednesday. The FBI arrested her Feb. 27 at a U.S. military facility in Irbil, Iraq, where she worked, court filings said.
Court filings do not elaborate on Thompson’s assignment, but Irbil has been home to an elite U.S. Special Operations counterterrorism effort.
“The conduct alleged in this complaint is a grave threat to national security, placed lives at risk, and represents a betrayal of our armed forces,” Timothy J. Shea, the U.S. attorney for the District of Columbia, said in a statement.
John C. Demers, the assistant attorney general for national security, said such conduct, if true, would be a “disgrace” and a “betrayal of country and colleagues.”
An attorney for Thompson could not be immediately reached for comment.
U.S. officials said the linguist, who had top-secret government security clearance, began repeatedly accessing classified information in Pentagon computer systems that she had no need to access on Dec. 30. The materials were accessed one day before protesters stormed the U.S. Embassy in Iraq in the aftermath of U.S. airstrikes against Iranian-backed forces in Iraq.
Thompson accessed 57 files concerning eight human intelligence sources, including names, photographs, personal identification and background data, and cables detailing information they had provided, according to an FBI arrest affidavit.
A court-authorized search of Thompson’s living quarters on Feb. 19 led to the discovery of a handwritten note in Arabic under her mattress containing classified information identifying three sources by name. The note also included a warning for a Pentagon target affiliated with a designated foreign terrorist organization with ties to Hezbollah, the Justice Department said. The note also instructed that the sources’ phones should be monitored, U.S. officials said.
Thompson allegedly used a video-messaging app on her phone to give information contained in the note to her unidentified co-conspirator, while knowing that the man has apparent connections to Hezbollah, which the State Department has designated a terrorist organization, the FBI affidavit said. Thompson knew the co-conspirator’s nephew worked for Lebanon’s Interior Ministry, the government alleged.
Separately, according to charging documents, Thompson is alleged to have turned over data identifying another human source and the information that person had provided.
In a statement, a Defense Department spokeswoman said it is cooperating with the Justice Department on the investigation and “taking all necessary precautions” in response to the alleged breach.