Just two days before the new year in Beijing, during a meeting with Toshihiro Nikai, the secretary general of Japan’s ruling Liberal Democratic Party, Chinese state councillor Yang Jiechi promised to help pave the way for the leaders of both countries to pay mutual state visits. Given the still somewhat chilly bilateral ties, Yang’s prospect of a summit between Prime Minister Shinzo Abe and President Xi Jinping, came as a fitting pre-new-year gift from Nikai.

However, the upbeat tone in bilateral ties was short-lived. Barely a fortnight into the new year came news of a Chinese People’s Liberation Army Navy (PLAN) frigate traversing the contiguous waters off the disputed Senkaku/Diaoyu Islands. This was not the first time a Chinese navy vessel was observed sailing near the isles. A foreign submarine traversing submerged close by, however, was unprecedented.

None of these vessels entered within the territorial sea limit of the Senkaku/Diaoyu Islands, which is twelve nautical miles. The identity of the submarine became a subject of speculation until the Japan Ministry of Defense confirmed it to be a Chinese Type-093B Shang-class nuclear-powered attack boat. Its nationality was clearly identified by the huge flag of the People’s Republic of China flown prominently off the sail of the submarine, which was photographed sailing northwest of the isles.

Slow-Boiling Tensions

This latest episode ignited a war of words between Beijing and Tokyo. While Japanese defense minister Itsunori Onodera described the submarine activity as “an attempt by China to unilaterally change the status quo in a new way and it also seriously escalates the situation,” the Chinese authorities defended the move as in line with international law—the same justifications it has used for coast guard and naval forays off the Senkaku/Diaoyu Islands. But Japan’s frustration was understandable, given encouraging signs of improving ties last year up till the meeting between Nikai and Yang.

It is worth noting that underneath the diplomatic niceties between the two Asian powerhouses not all has been well. The Sino-Japanese dispute in the East China Sea has been simmering, even if on a slow boil unlike the more explosive aftermath following two other high-profile incidents. First, the clash between the Japan Coast Guard and a Chinese trawler off the Senkaku/Diaoyu Islands in September 2010 sparked an uproar, and, two years later, so did Tokyo’s decision to nationalize the isles.

In early January the International Hydrographic Organization approved Tokyo’s proposals for naming thirty-four seabed features in the East China Sea—more than those granted to Beijing. This development could be well regarded as a victory of sorts for Tokyo, which has long been wary of Beijing’s increasingly assertive maritime activities in the East China Sea, including the latter’s gas drilling in a disputed area close to Japan’s proposed median line separating both countries’ exclusive economic zones in August 2017. From Beijing’s standpoint, however, this move would reinforce Japan’s assertion of control over the waters.

Therefore, despite apparent moves by the two capitals to improve ties, there is no way to discount the evolving signs of trouble in the East China Sea, especially over the still lingering dispute over the Senkaku/Diaoyu Islands. Much deeper than this, however, has been the enduring historical animosities. Little wonder that one of the first New Year editorials published by the Global Times proclaimed loudly with the headline “Tokyo-Canberra ‘quasi alliance’ threat to peace” and not long after, a Xinhua news report about Beijing’s commencement of compiling previously missing historical records from the fourteen-year Chinese People’s War of Resistance against Japanese Aggression.

This Sino-Japanese schism looks set to persist for a long time. At least for now, Abe does not appear keen to roll back on earlier policies regarding the Senkaku/Diaoyu Islands issue. And neither is Xi about to abandon his policies on the same. Given that the two countries are effectively deadlocked on the dispute, Tokyo’s sounding an alarm bell about the latest Chinese submarine foray foretells an unsettling future.

It is necessary to consider the established patterns of Beijing’s maritime activities in the area as the context to understand why that is the case.

Zonal Creep

After Tokyo governor Shintaro Ishihara announced plans of the metropolitan government to purchase some of the Senkaku/Diaoyu Islands in early 2012, Chinese coast guard vessels initially started to traverse outside the twelve-nautical-mile territorial sea limit of the isles. The first such forays were observed on May 3, conducted by a pair of Fisheries Law Enforcement Command patrol ships Yuzheng 203 and Yuzheng 204. Notwithstanding Japan’s protest, Chinese officials defended the mission as “routine” and claimed that Beijing had “every right” to do so.

Chinese civilian government vessels continued to restrict their movements outside the Senkaku/Diaoyu territorial sea limits, until September of that year, which is when the Japanese government formally decided to purchase the isles. Not long after the State Oceanic Administration published a document titled China's Island Protection Law, which declared the Senkaku/Diaoyu Islands as the starting point of its territorial waters, on the first Chinese surveillance ships entered the twelve-nautical-mile limit of one of the isles on September 14. Beijing pledged to standardize surveillance of the isles and undertake “tit-for-tat measures” to protect its territory as the situation develops.

Later the same month, when an unusually large flotilla of coastguard vessels loitered in both the contiguous zone and the territorial waters, a pair of PLAN frigates was observed nearby. This was confirmed by the Chinese defense authorities, who remarked that the navy patrols could “quickly react to maritime and airspace emergencies” in the area. The warships did not enter the territorial waters, but the episode clearly demonstrated that the PLAN stood ready to reinforce the coastguards if things turned awry.

Since then, no further Chinese “naval backup” was observed loitering close to the Senkaku/Diaoyu Islands. But Chinese coast guard vessels gradually routinized their forays into territorial waters off the Senkaku/Diaoyu Islands, ignoring warnings by their Japanese counterparts. The vessels would often stay for prolonged periods within instead of mere transit through the zone. Tension in the East China Sea escalated in January 2013 after a PLAN frigate illuminated its fire control radar at a Japan Maritime Self-Defense Force (MSDF) helicopter, followed less than two weeks later by another incident, during which another Chinese frigate illuminated a Japanese destroyer “for minutes” with its fire control radar, on high seas north of the disputed isles.

There were subsequently no further, similar Sino-Japanese naval encounters on the high seas—although the forays made by the Chinese coast guard to the Senkaku/Diaoyu islands normalized into a regular pattern. Early November 2014 promised a respite, after Yang Jiechi and Japanese national security advisor Shotaro Yachi reached a four-point agreement aimed at ameliorating tensions in the East China Sea. Soon after, Abe and Xi met on the sidelines of the Asia-Pacific Economic Cooperation Summit, during which they stressed the need to tamp down on tensions, especially over the Senkaku/Diaoyu Islands.

Over the two weeks following the Abe-Xi meeting, there were no observed Chinese coast guard movements around the isles. But Chinese actions on November 25 broke that brief respite. That is when three China Coast Guard vessels entered and remained in the territorial waters for two hours before departing. Having believed that ties were on the mend following the earlier diplomatic breakthroughs, Tokyo was naturally upset by the latest development. Thus, 2014 ended with a pair of PLAN warships traversing as close as seventy kilometers off the disputed isles. Again, Beijing was unfazed about Tokyo’s protests.

Capability Creep

Since December 2014, no further unusual PLAN activities were spotted close to the Senkaku/Diaoyu Islands even though Chinese naval vessels began to routinely transit strategic waterways through the Japanese Archipelago, the Miyako Strait in particular, on their way to the Western Pacific open waters for training. But Beijing had plans to up the ante even as Tokyo was lulled into set patterns of CCG activities off the isles.

In November 2015, a PLAN Dongdiao-class intelligence-gathering ship was spotted within the Senkaku/Diaoyu contiguous zone, though it did not breach the territorial sea limit. Describing this latest move as “unusual.” Tokyo mulled deploying MSDF vessels to the area in the event PLAN ships enter the territorial waters off the isles, despite Beijing’s insistence that the vessel was “conducting normal activities” in line with international law.

The following month, Beijing flashed another new card—this time a never-before-seen CCG vessel, Haijing 31239, traversed the Senkaku/Diaoyu contiguous zone. The media was awash with reports about this unprecedented Chinese move of sending an armed coast guard vessel to the disputed waters. But this descriptor is misleading. To begin with, virtually all Chinese coast guard vessels are armed to a certain degree given their law enforcement role. More accurately, Haijing 31239 sported an armament heavier than those which hitherto took part in the Senkaku/Diaoyu forays. It was a former PLAN Jiangwei-I guided-missile frigate with most of its high-power combat systems, especially its missiles, removed and leaving behind four twin mountings of thirty-seven millimeter autocannons.

Therefore, Haijing 31239 was not the first “armed coast guard vessel” as purported, but the first so heavily-armed ever deployed to the disputed isles. This represented an escalation in the type of coast guard capability Beijing chose to utilize. Four days after its debut appearance, the same ship “upgraded” its presence from contiguous zone to territorial waters off the isles. And following a hiatus, in June 2016, the PLAN intelligence-gathering ship appeared off the contiguous zone of the Senkaku/Diaoyu Islands. The same exchange of diplomatic barbs revolved around Tokyo’s concerns about the Chinese military “unilaterally escalating its actions” and Beijing justifying the ship’s presence as being in line with international law.