Tensions between China and Japan over the sovereignty of the Senkaku (Diaoyu) islands, located in the East China Sea, and currently administered by Tokyo, have been escalating for some months.
Tokyo's and Beijing's claims to the islands (which are also, incidentally, claimed by Taiwan) are backed up by frequent deployments of paramilitary patrol craft of the two nations' coast guards.
The dispute took a new turn, however, on January 11, when a submarine, subsequently identified as a 7,000-tonne Type 093 Shang-class nuclear-powered attack boat of China's PLA Navy, surfaced in the Japan-claimed contiguous zone near the Senkakus, and promptly hoisted a Chinese naval ensign.
The sub was reportedly then joined by a by a PLA Navy surface warship, namely a Jiangkai-II class guided missile frigate.
According to regional maritime security sources the Japan Maritime Self Defence Force (JMSDF) had been tracking the Shang submarine on its submerged approach to the since at least January 10, probably utilising both the underwater hydrophone array which reportedly stretches between the Japanese home islands, Okinawa, and the Senkakus, and one or more JMSDF diesel-electric attack submarines.
After it had surfaced, the Chinese submarine was shadowed by a pair of JMSDF warships, the Abakuma corvette Oyado, and the Takanami destroyer Onami, as well as a JMSDF P- 3C Orion maritime patrol aircraft. Active sonar was apparently used by the Japanese warships to warn off the Chinese submarine.
This incident not only marked a significant escalation of naval involvement in the Senkakus dispute, it was also the first reported instance of Beijing making use of "submarine diplomacy". The sudden appearance in theatre of an attack submarine, or even the rumoured presence of such a vessel, can have an effect which is quite disproportionate to its capabilities.
Analysts are speculating on the motivation behind China's apparent recalibration of its strategy over the Senkakus. Tokyo's backing of US President Donald Trump's "Indo Pacific" concept is a possible significant factor. Recent rulings by the International Hydrographic Organisation, which allocated Japanese names to a number of undersea features in the East China Sea, and a desire to test the efficacy of Japan's underwater defences, may also have been motivations for the Chinese action.
