TOKYO -- Japanese officials are pondering the meaning of a Chinese navy spy ship's passage near disputed East China Sea islets, a move some think is connected with Beijing's self-declared air defense identification zone (ADIZ) over that body of water.
A Japanese P-3C reconnaissance plane spotted the Dongdiao-class surveillance vessel, pennant number 855, on the evening of Nov. 11 south of the Japanese-controlled Senkaku Islands, which the Chinese claim and call the Diaoyu.
Chinese maritime police are not an uncommon sight in these waters, but this marked the first time that a People's Liberation Army Navy vessel was seen sailing there.
The ship gave an evasive response when asked the purpose of its passage. It left the area the following night.
Japan's Defense Ministry went public with the ship's "peculiar" activity. What caught officials' eye was its route. The vessel sailed one-and-a-half laps through the waters from east to west before departing westward.
Officials say it followed part of the boundary of China's East China Sea ADIZ, which Beijing unilaterally declared in 2013 and covers the islands, overlapping Japan's ADIZ. Such zones are meant to provide advanced notice of whether planes approaching territorial airspace come as friends or foes.
A government source speculates that China was "trying to flex its muscles." The move has made Japanese defense officials uneasy. Should Chinese warships return to the area regularly, Japan will have to step up its patrols, raising the risk of an inadvertent clash.
Chinese foreign ministry spokesman Hong Lei insisted that the Chinese navy's activities are in complete accordance with international law, but he did not elaborate on the spy ship's purpose for sailing near the islands.
Officials within the Japanese government are not sure that the vessel was intentionally following the zone. With Beijing's intentions a mystery, Japan is expected to keep a closer watch on the area.
