Officials from the UK Ministry of Defence (MoD) have acknowledged to accidentally circulating a NATO report containing military codes and other military tactics that were supposed to be used in two war games taking place in UK waters, The Herald reports.

The NATO document labeled as "NATO restricted" contained 192 pages of information such as radio frequencies, radio jamming rules, GPS coordinates, military codewords, call signs, aircraft “killbox” target areas, code decryption tables, and authentication protocols.

Besides military tactics, the document also included a long list of phone numbers, email addresses, and military facilities, of all the parties involved in the war games.

MoD officials sent the document via an email to multiple fishing and ferry operators on March 29. The NATO file was attached to the email by accident. The fishermen and ferry operators were supposed to receive a timetable of the two war games, and how their normal day-to-day operations would be affected.

Email mishap leads to serious data leak

NATO scheduled two war games around the UK. The first is Joint Warrior 161, a joint naval exercise taking place around Scotland's waters from April 11 to 23, involving 3,400 troops, 40 aircraft, 22 ships and four submarines. The second is Griffin Strike 16, taking place around the South-West coast of England and Wales.

The NATO document contained information specific to these two joint NATO exercises, but also general military tactics employed by NATO units, which other adversary states would like to get their hands on.

Such types of documents are kept under a close guard, and this leak is a rare event. Other nation states would normally spend a lot of time and effort to hack military personnel in order to find and extract such detailed information.

The British press and officials have called for an investigation following this embarrassing mishap. A MoD spokesman told The Herald, "A communications issue around the Joint Warrior and Griffin Strike exercises was identified and appropriate measures have been taken. There is no impact to the public, military personnel or units participating in the exercise."