Japan and China plan to step up military exchanges with a visit to Japan by the Chinese defense minister and the first-ever port call by a Chinese naval vessel, an official said Wednesday, amid signs of warming ties between the neighbors.

Both sides are trying to arrange a visit by Chinese Defense Minister Cao Gangchuan at an early date and are also making preparations for the naval port call, a Defense Ministry spokeswoman said on condition of anonymity, citing ministry protocol.

Details have not been set, and the spokeswoman said she could not confirm a report by the Nikkei newspaper that Cao could visit as early as September. The naval exchange could take place in October, the report said.

A Chinese defense minister last visited in 1998, and there has never been a port call by a Chinese naval ship to Japan.

Prime Minister Shinzo Abe traveled to China in October, immediately after taking office, in a bid to reverse the steep deterioration in ties under his predecessor, Junichiro Koizumi. Distrust lingers over Japan's handling of its wartime history and China's rapid military expansion.

The military exchanges are one way to encourage transparency in Chinese military spending, the Nikkei said. Tokyo also wants to use the contacts to explain to Beijing that its joint U.S. missile defense system is not targeted at China, the report says.