TOKYO -- While China prepares to welcome Japanese Prime Minister Shinzo Abe to Beijing next week, the two nations are engaged in a military chess game beneath the surface, in the Asian seas.
Competing for maritime supremacy, both sides are flexing their submarine warfare capabilities in each other's backyards. Japan recently announced for the first time that it had conducted undersea drills in the South China Sea. This follows China's participation in Russian drills held in the Sea of Japan last year.
Last month, Japanese military experts closely watched the movement of 28 Russian vessels that entered the Sea of Japan from the Sea of Okhotsk to the north.
The presence of one ship in particular caught their attention: the Igor Belousov search-and-rescue vessel, which is designed to provide assistance to distressed submarines.
Submarine rescue is known to be an area that the Chinese are working to improve, knowing that they lag behind the U.S. Navy as well as the Japanese Maritime Self-Defense Force in that capability.
"There is a chance that the Chinese military sent submarines to the Sea of Japan to train with the Russians, or that they will do so in the near future," a source familiar with Japanese national security matters said.
After being disinvited from Rimpac, the American-led Pacific war games, earlier this year, China has been looking for ways to learn submarine rescue techniques from other countries.
Russia is the natural partner. In late September, China took part in Vostok-2018, the biggest war games conducted on Russian soil since the Soviet era. About 3,000 Chinese troops maneuvered in Siberia, along with 900 military vehicles.
When Russia conducted naval drills in the Sea of Japan in September 2017, China sent a submarine search-and-rescue ship. Experts therefore believe that Beijing may send submarines to the same area for the purpose of learning more from the Russian navy.
While massive aircraft carriers and stealth fighter jets receive the most attention, the true "game-changers" of naval strategy today are said to be submarines.
The Japanese Maritime Self-Defense Force can detect, with a high degree of certainty, submarines passing through nearby straits. The SDF seldom flaunts this capability, keeping its tracking competency close to the vest.
China is busy building aircraft carriers, but they require an escort of submarines to be effective in combat. Ballistic missile submarines, which China has deployed to the South China Sea, also require the protection of escort subs.
So China is recruiting Russia as an instructor to develop its crews' defensive convoy skills.
By scale, China's submarine fleet of roughly 60 submarines outnumbers Japan's 22. But Japan is said to maintain significant leads in vessel operations and conducting silent voyages.
By taking the unusual step of announcing it had carried out submarine war games in the South China Sea, Japan is sending a clear message to China and its neighbors: Chinese subs will not come out unscathed if conflict were to break out within those disputed waters.
At the same time, Tokyo seemed to have demonstrated to Washington that it can play a role in the U.S. containment of Chinese submarines in the South China Sea.
China's military has long relied on quantity to compensate for the gap in quality. That suggests China's flotilla of submarines will grow further still. In addition, its navy is looking to beef up its strategy of asymmetry by deploying a large number of unmanned underwater vessels. That will require Japan to focus on numbers as well as submarine tech.