Japanese Defense Minister Takeshi Iwaya has apologized for another mistake found in a study for the deployment of a US-made Aegis Ashore missile defense system.
Iwaya told reporters on Tuesday that the inaccuracy was discovered in a survey of the environmental effects of the radio waves from the system's powerful radars.
He said a ministry employee made a mistake when inputting numerical data from a subcontractor. He said the error was inexcusable.
The ministry insists the overall study is sound, and says the error has no impact on the suitability of the deployment site.
The ministry has chosen a Self-Defense Forces training area in the northern city of Akita as one of two candidate deployment sites.
Local government officials and residents were already angered by the ministry's use of incorrect topographical data in the selection process.
They were further enraged when a defense official dozed off in a meeting to apologize for the mistake.
Meanwhile, documents related to the other candidate site, in Yamaguchi Prefecture, were found to contain inconsistent topographical data from cited sources.
Ministry officials have indicated they will provide an explanation after additional surveys are carried out.