Japanese Foreign Minister Taro Aso states the obvious. From the AP:

Japan has long listed China's military expansion as a top security concern in the region but the remarks by Japanese Foreign Minister Taro Aso were unusually blunt and echoed U.S. concern about Beijing's military spending. ''It's a neighboring country with nuclear bombs, and its military expenditure has been on the rise for 12 years. It's beginning to pose a considerable threat,'' Japanese Foreign Minister Taro Aso told a news conference.... ''China is fanning threat and anxiety,'' Aso said. ''The content of China's military expenditures is difficult for outsiders to know, and that fuels suspicion.''

See comments of Dan Blumenthal, former senior director for China, Taiwan and Mongolia in the Secretary of Defense's Office of International Security Affairs and current AEI fellow, here.