Accidents or incidents involving U.S. military aircraft in Japan more than doubled to 25 cases in 2017 from 11 the year before, Defense Minister Itsunori Onodera has said.

Onodera said Monday that the Defense Ministry conducted an assessment of the issue after he was told by U.S. Pacific Command chief Adm. Harry Harris earlier in the month in Hawaii that the number of accidents had decreased in 2017.

"Based on the information we have at hand, (accidents are) increasing," Onodera told reporters. Another senior official said the ministry is not aware of what data Harris was referring to during talks with Onodera on Jan. 9.