Tokyo and Beijing are certainly rivals, but given demographic trends, the rivalry will be among grumpy old men.
Things are heating up in the East China Sea, as China continues to pressure Japan to abandon its claim that its sovereignty over the Senkaku Islands (called the Diaoyus by China) is nonnegotiable.
And after a year of dangerous intrusions and escalations, such as a Chinese frigate locking its radar on a Japanese vessel around the disputed islands, recently Japanese Defense Minister Itsunori Onodera accused China of sending its coast guard vessels into the Senkaku waters more than once a week: "I believe the intrusions by China in the territorial waters around the Senkaku Islands fall in the 'gray zone' [between] peacetime and an emergency situation."
The Sino-Japanese dispute is coming perilously close to conflict, as China finds in Shinzo Abe's government a wall of resistance to its recent pattern of aggression in its near seas. Abe has ambitious plans for reviving both the Japanese economy and its national security institutions to deal with dual threats from China and North Korea.
But there is some irony in Onodera's choice of words, "gray zone," to describe the state of affairs in the East China Sea: This great-power competition is unique in that the protagonists are getting old fast.
Never before have we seen a strategic rivalry in which the opposing sides are getting so old. While both countries are using the tools of traditional statecraft -- rising military budgets, high-stakes diplomacy, economic leverage -- to gain strategic advantage, they are rapidly losing the actual people to sustain this great game.
According to Chinese statistics, the 15-64 age-group cohort, the most productive age group, shrank by 3.45 million last year. Meanwhile, the China Research Center on Aging announced that there are now 202 million elderly in China -- the size of a large country.
According to my colleague Nicholas Eberstadt, the demographic guru, China's working-age population will shrink at a rate of 1 percent starting soon (if it hasn't already). By way of contrast, during the past three decades of massive economic growth, China's working-age population grew by 1.8 percent per year. The cohort of Chinese 65 and older will grow at an astonishing rate of 3.7 percent per year for the next two decades; the elderly as a percentage of the entire population will double, reaching 17.2 percent by 2030.
As for Japan, more than 23 percent of the population is already 65 or older. Over the next few decades the proportion of elderly in Japan could grow to one-third of the total population Already, the total population is shrinking and not being replaced through either birth or immigration. Over the next two decades, the working-age population will decline by about 17 percent from 81 million to 67 million.
Each country will lose military-age personnel needed to populate its increasingly sophisticated military capabilities or innovative industrial bases that build greater wealth and power. Accompanying the erosion in wealth and power will be a loss of political will to meet current leaders' ambitions.
The costs of the coming old-age tsunami are mind-boggling. China is relatively poor and has no national pension system and a limited patchwork of locally run systems. Japan is far wealthier but deeply indebted. Neither country has enough kids to support aging parents.
It would be easy enough to conclude that these demographic trends portend more inward-looking countries tending to their elderly. But there is nothing inevitable in international politics -- aging countries do not necessarily make more peaceful ones. And these are long-run trends; there can be much trouble before they're all old.
While it is amusing to consider that the walker may replace the missile as the weapon of choice for China and Japan, there are also far more dangerous possibilities. An aging Russia, for example, relies on its nuclear weapons (the most bang for the least manpower) for security. Both Japan and China are seriously interested in drones and robotics as systems of the future. Given the inclinations of youth in both countries, conflict may seem like a complicated video game.
And like grumpy old men, the countries may become more impatient and disputatious. Where this plot leads is anyone's guess, but for guidance we are better off searching in the science-fiction section of the library.