The FBI arrested a CIA agent Tuesday who has been charged with leaking top secret materials relating to Israel’s plan to potentially retaliate against Iran over its recent missile attack.

Asif W. Rahman was employed by the CIA overseas and held a top-secret security clearance, a prerequisite for his position, The New York Times reported. The FBI arrested him in Cambodia after classified information began circulating online in October that discussed Israel’s reported intention of striking back against Iran after it unleashed a series of missile attacks against Israel on Oct. 1.

The files were prepared by the National Geospatial-Intelligence Agency and contained specific satellite imagery linked to the possible Israeli air strikes and also exposed what kind of missiles might be available for the retaliatory strike.

The top secret documents were reserved for officials possessing the necessary security clearance within the US or members of the Five Eyes intelligence group that includes the US, Australia, Canada, New Zealand and the UK. The Middle East Spectator said it was in possession of the documents and had received them through an anonymous source who was not linked to the individual who first leaked the information. It also said it could guarantee that the documents were real, the New York Post reported.

The FBI revealed in October that they were investigating the matter, saying that it was “working closely with our partners in the Department of Defense and intelligence community.” The indictment against Rahman doesn’t indicate how the leak occurred but isolates the timing to about Oct. 17.

FBI investigators believe the information was stolen in Cambodia, according to court papers. Rahman would have had sufficient security clearance to have access to the highly classified and sensitive documents.

Over a million people in the US have top secret security clearances, The Post noted. They work in intelligence, police and defense. Another 1.6 million have security levels that allow them to view secret or confidential government documents. A security clearance can be revoked for a multitude of factors, from mislaying a classified document to being convicted of a criminal offense.