Representatives of the Japanese Ministry of Education were called as witnesses by the Accident Investigation Board in charge of discovering the true nature of the Fukushima nuclear disaster. During questioning it was determined that the predictive data from SPEEDI, which forecasts and predicts spread of radioactive material after a nuclear disaster, had been provided to the U.S.Military.
According to NHK, the data had been compiled immediately after the accident, and provided to the US through the Foreign Ministry. The Ministry of Education decided that the published data did not accurately predict the actual situation, and may have lead to unnecessary confusion if released to the public. For these reasons the data was not published immediately, and evacuees were abandoned to make decisions with the government only telling part of the story.