A Royal Navy submariner faces trial in November for passing top secret code words and code technology to an enemy of the UK.
Petty Officer Edward Devenny appeared at the Old Bailey by video link from a prison cell where he's been held since his arrest earlier this year.
Devenny is accused of breaching the Official Secrets Act between 18th November 2011 and January 28th 2012.
The charges specify he "collected code words, sketches, documents and other articles" relating to "crypto material" and that he "communicated them to an enemy".
This information was allegedly "prejudicial to the safety or interests of the state". 29-year-old Devenny is from Strabane in Northern Ireland. He has not yet entered a plea for legal reasons.