The arrest came as leaked NSA documents appeared to show details of a Russian cyberattack on US election officials
A US intelligence agency contractor has been charged with leaking 'classified materials' to a media outlet.
The US Justice Department says Reality Winner (25) was arrested on Saturday, and appeared in court yesterday afternoon.
The details of the arrest were announced shortly after news website The Intercept published and reported on a supposed classified NSA document, which appears to show details of an attempted Russian cyberattack targeting US election officials in the days ahead of last year's presidential election.
It was not immediately clear whether Ms Winner's arrest was linked to the published document.
In forms detailing Ms Winner's arrest, officials say they became aware of the leak after journalists contacted the intelligence agency in connection with the classified documents.
The FBI alleges that the documents "appeared to be folded and/or creased, suggesting they had been printed and hand-carried out of a secured space".
The arrest affidavit adds: "[An] audit of the six individuals' desk computers revealed that Winner had e-mail contact with the News Outlet. The audit did not reveal that any of the other individuals had e-mail contact with the News Outlet. "
In a statement, the US Justice Department claims Ms Winner admitted to printing the documents and mailing them to the news agency.
US Deputy Attorney General Rod Rosenstein said: "Releasing classified material without authorisation threatens our nation’s security and undermines public faith in government. People who are trusted with classified information and pledge to protect it must be held accountable when they violate that obligation."
In a statement quoted by the Daily Beast, The Intercept said it had "no knowledge of the identity of the source" of the document it published.
According to the file, Russian intelligence actors engaged in a "voter registration-themed spear-phishing campaign targeting US local government organisations", which saw emails sent containing malicious code.
The document itself stresses it is unknown how successful the alleged cyberattack was, with the authors noting: "It is whether the aforementioned spear-phishing deployment successfully compromised the intended victims, and what potential data could have been accessed by the cyber actor."
The Intercept reporter Sam Biddle added that there is nothing "indicating the actual voting machines or vote tabulations were compromised".
very very important: there’s nothing in the NSA report indicating the actual voting machines or vote tabulations were compromised— Sam Biddle (@samfbiddle) June 5, 2017