Japanese Defense Minister Itsunori Onodera said that a Chinese frigate directed its fire-control radar at a Japanese destroyer Jan. 30 near disputed islands in the East China Sea, The New York Times reported.
The uninhabited island group known as Senkaku in Japan and Diaoyu in China has been controlled by Japan for decades but China and Taiwan claim it.
The Japanese Defense Ministry also disclosed Tuesday that a Chinese frigate directed the same kind of radar at a Japanese military helicopter in a previously undisclosed incident that occurred on Jan. 19.
The ministry said in both cases the Chinese ships eventually turned off their radar without actually firing a shot.
The use of such radar was a threatening gesture that represented an increase in tensions, Japan said.