JAPAN'S protest to China that its warships recently locked their weapons-control radars onto a Japanese navy destroyer and a military helicopter raises disturbing questions.
In these two separate incidents, not far from the bitterly disputed Senkaku or Diaoyu Islands in the East China Sea, one question is the extent to which effective civilian control is being exercised over China's armed forces.
If China's military, or rogue ultra-nationalist officers, are calling the shots in a crisis that potentially involves not just Japan but also its ally, the United States, it could trigger a wider war with consequences that would destabilise the Asia-Pacific region.
Japan's Defence Minister Itsunori Onodera warned China last Thursday that it may have violated the United Nations Charter by threatening force against Japan, which administers the uninhabited Senkakus in the teeth of rival ownerships claims from China and Taiwan.
In an apparent sign of escalating militarisation in the dispute, the Chinese navy's use of weapons-targeting radar last month was considered highly threatening by Japanese military commanders because it could signal preparations for a missile attack.
A defence ministry official in Tokyo said that in both radar incidents, Japanese commanders took "standard evasive manoeuvres", like changing course, but did not engage their weapons systems.
The Japanese destroyer was targeted "for several minutes" on Jan 30 by a Chinese frigate about 3km away, the official said, while a ship-based Japanese military helicopter was locked onto 11 days earlier.
The Jan 30 incident occurred in international waters about 100km north of the disputed islands.
Since Japan nationalised the islands last September, China has taken increasingly intense measures to challenge Tokyo's control, with Chinese jet fighters and warships replacing unarmed coast guard-type planes and vessels in several of the latest encounters.
A key question is who is authorising the Chinese build-up and the actions taken that could lead to an exchange of fire?