Tokyo: Four Chinese navy ships sailed through a zone just outside Japanese territorial waters between Yonaguni and Iriomote islands in Okinawa Prefecture early Monday and left the zone about five and a half hours later, the Defense Ministry said.
The warships were heading northward, a direction which would have taken them to a similar zone near Japanese waters around the disputed Senkaku Islands, but they turned northwestward about 40 kilometers north-northeast of Yonaguni at around 10 am, possibly to avoid entering the zone.
Sailing through such zones near a nation`s territorial waters, called a contiguous zone, is permitted under international law.
When Chinese warships sailed through the same area near Yonaguni Island in a similar direction in October, they, too, later changed course to avoid coming close to the uninhabited Senkaku Islands in the East China Sea, which are also claimed by China.
A Maritime Self-Defense Force patrol aircraft and an MSDF destroyer spotted the ships, consisting of two destroyers and two frigates, sailing north-eastward about 49 km south-southeast of Yonaguni Island at around 5 am, leaving the Pacific Ocean, the ministry said.
The same four ships sailed from the East China Sea to the Pacific on high seas between the main Okinawa Island and Miyakojima Island on November 28 and engaged in drills involving helicopter flights and refuelling in the Pacific, according to the ministry.
Relations between Japan and China have soured considerably since the Japanese government purchased most of the Senkaku Islands, called Diaoyu in China, from a private Japanese national in September, a move that led to sometimes violent protests across Chinese cities.