A member of the Ground Self-Defense Force (GSDF) Middle Army Headquarters lost a USB flash drive containing unit deployment maps used in Japan-U.S. exercises, but the loss was covered up, it has emerged.

The memory stick, which was lost in February last year, contained maps showing U.S. helicopter and tank placements. However, the loss was covered up, and acting Defense Minister Fumio Kyuma and U.S. officials were not informed.

"I made the decision not to disclose the matter, but perhaps I should have reported it to the United States," said GSDF Chief of Staff Ryoichi Oriki, who at the time was Middle Army chief commander.

After information on an Aegis-equipped destroyer was leaked in March last year, U.S. officials are believed to have protested, asking why Japan, as an ally did not understand the importance of confidential information. In light of the leak, the response to the latest incident, which was covered up, is likely to gain attention.

About 4,800 GSDF and U.S. military members participated in the map exercises, which were held at GSDF Camp Itami between Feb. 8 and 16 last year. There were many tents set up at the camp, and computers and maps were brought in, with troops being moved to match envisaged enemy movements.

Sources close to the incident said that the USB flash drive contained the envisaged scale of enemy troops, and other undisclosed information used in map exercises, such as training maps showing the placement of GSDF and U.S. military helicopters and tanks. A GSDF lieutenant colonel handling information during training on Feb. 14 last year handed the memory stick to a sergeant first class, and asked for work to be carried out. After finishing the work the subordinate left the flash drive on a desk and went home. The next day, however, it was gone. SDF police searched for it, but it was not found.

The information on the storage device was classed as information requiring caution, and its loss did not warrant criminal charges. Officials were not required to report the loss to the Minister of Defense, but checks were not made with U.S. officials about information pertaining to the U.S. military, and it remains unclear whether the classification of information requiring caution was appropriate.

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