NY Times 
February 5, 2013
TOKYO — Japan lodged a formal protest with the Chinese government on Tuesday after it said a Chinese warship directed a radar used to aim missiles at a Japanese warship, in a new escalation of a standoff over disputed islands.
The Japanese defense minister, Itsunori Onodera, said that a Chinese navy frigate had directed its fire-control radar at a Japanese destroyer in the incident on Jan. 30 near the islands in the East China Sea, known as the Senkaku in Japan and Diaoyu in Chinese. The uninhabited island group has been controlled by Japan for decades, but claimed by China and also Taiwan.
On Tuesday, the Defense Ministry also disclosed that a Chinese frigate had directed the same kind of radar at a Japanese military helicopter in a previously undisclosed incident on Jan. 19. In both cases, the Chinese ships eventually turned off the radar without actually firing a shot.
Still, Japanese officials said the use of such radar was a threatening gesture that represented an increase in tensions, which have been growing since the Japanese government announced last summer that it would buy three of the five islands. The Chinese responded by sending paramilitary surveillance ships into or near Japanese-claimed waters around the islands on an almost daily basis. Those incursions were intercepted by Japanese coast guard ships in a high-seas game of cat and mouse.