Defense Minister Itsunori Onodera says his ministry will investigate why the Ground Self-Defense Force waited a year before reporting to the ministry about the discovery of official documents that it had earlier said it could not find.
Japanese Foreign Minister Taro Kono is expected to visit South Korea next week in connection with the inter-Korean summit planned for late April.
Foreign Minister Kono says Japan has lodged a protest with both Russia and the United States over a joint project on one of 4 Russian-controlled islands claimed by Japan.