Defense Minister Fumio Kyuma's office received an envelope that contained a razor blade in the mail earlier this month, his office said Wednesday.
No one was hurt but the office reported it to the Metropolitan Police Department as a case of harassment.
A razor blade was placed inside a folded piece of paper in the envelope, and the paper had a handwritten message criticizing Kyuma's position as soft with regard to his recent visit to the United States, the office said.