The following is the second instalment of a series focusing on the confrontation between Japan and China over the Senkaku Islands in Okinawa Prefecture.
Chinese military assertiveness has been growing increasingly conspicuous.
On July 25, a P-3C patrol plane of the Maritime Self-Defence Force spotted five Chinese military vessels, including a destroyer, sailing in waters near the Nansei Islands, about 100 kilometers northeast of Miyakojima island, southwest of Okinawa's main island.
It was later confirmed that the Chinese ships had entered the Pacific Ocean by way of Soya Strait between Hokkaido and Sakhalin Island after conducting joint live-ammunition firing exercises with the Russian Navy in the Sea of Japan off Vladivostok.
That meant the Chinese military vessels had, for the first time ever, circumnavigated the Japanese archipelago.
A day before the passage through Soya Strait, a Chinese early warning plane, Y8, had flown in the airspace between Okinawa's main island and Miyakojima island.
It was also the first time that a Chinese military plane had crossed over China's self-designated "First Island Chain" to intrude into Japan's airspace over the Pacific.
The First Island Chain is what the Chinese Liberation Army's Navy has designated in reference to a series of island groups spanning the southern part of Kyushu, the Nansei Islands, Taiwan and the Philippines.
What it refers to as the "Second Island Chain" comprises the line stretching from the Izu Islands and Ogasawara Islands, both administered by the Tokyo metropolitan government, over to Papua New Guinea, by way of Guam and Saipan.