Monica Witt, 39, was accused of switching sides after more than a decade of USA military service and identifying American intelligence officers and their personal Facebook accounts for the Iranian regime.
The US also indicted four Iranians working for the Revolutionary Guard who, using information Witt provided them, targeted her former colleagues in US intelligence with malware and phishing scams in hopes of accessing their computer networks.
"On or about July 3, 2013, Witt wrote Individual A, 'I think I can slip into Russian Federation quietly if they help me and then I can contact WikiLeaks from there without disclosing my location", the indictment said. She was a Defense Department contractor at the time.
In February 2012, Witt traveled to Iran to attend a conference. "She chose to turn against the United States and turn her loyalties to Iran", FBI Executive Assistant Director Jay Tabb told reporters.
The four Iranians were acting on behalf of the government-linked Iranian Revolutionary Guard, prosecutors said. That group has been designated by the USA government as promoting terrorism. Weeks later, she moved to Iran and began compiling the personal information of her former colleagues into "target packages", which the IRGC used to target American intelligence agents. "Thanks for giving me the opportunity", according to the indictment. It said she replied: "Well, I loved the work, and I am endeavoring to put the training I received to good use instead of evil".
They are said to be charged with using malware, phishing attacks and false identities, including one called Bella Wood on Facebook, who successfully friended one of the USA agents while they were deployed as a military intelligence officer in Kabul.
"Our intelligence professionals swear an oath to protect our country, and we trust them to uphold their oath".
WASHINGTON, DC - OCTOBER 04: Assistant U.S. Attorney General for National Security John C. Demers (2nd L), United States Attorney for the Western District of Pennsylvania Scott W. Brady (R), and FBI Deputy Assistant Director for Cyber Division Eric Welling (L) listen during a news conference to announce criminal charges on October 4, 2018 in Washington, DC. "But every great while, one of these trusted people fails us".
In the few weeks before her defection, Witt is alleged to have conducted searches on Facebook for the names of former fellow counter-intelligence agents, and the spouse of one of them.
At least one of those New Horizon conferences was organised by Iranian-American journalist Marzieh Hashemi, who was detained by United States officials in January as a material witness in a federal criminal case, according to the Tehran Times.