(CNN) US and Russian warships nearly collide in the Pacific. Quoting Carl Schuster,

“Putin clearly has ordered the Russian Navy to pressure the USN whenever opportunities exist. It may possibly be a show of political support for China while Xi is in Moscow, but more likely to signal that Russia is willing to challenge the US dominance on the world stage and at sea,” he said.

More specific reasoning can be applied.   Russia and China share a long land border, with the seeds of conflict:

• Sino-Soviet border conflict of 1969, which was coupled with the request of the Brezhnev government to pre-emptively strike China with nuclear weapons. (Telegraph) USSR planned nuclear attack on China in 1969.
• Sino-Soviet conflict of 1929, directly about control of the Chinese Eastern Railway, built originally as as Russian concession. It became emblematic  of conflict over business concessions and seizures of territory that comprise much of the current eastern border of Russia.
• The root of it is the three way contest between Japan, Russia, and China for Manchuria, with the cheating of China codified in the Unequal Treaties.

The weakness of the Qing dynasty was  obvious in the inability to assert control over northern Manchuria, which became the plaything of Russia-Japan rivalry. Until 1860, Vladivostok was part of China.  One of the historical constants of relations between land powers, modified, perhaps only temporarily, by nuclear weapons, is lust for land, and the patriotic urge to regain what was seized. It is so common a theme, historians have a word for it, revanchism.

It is safe to say that in the inner recesses of diplomatic thought, China has a revanchist urge. Vladivostok will one day (again) be part of China, as surely as Taiwan. Russians can hardly repress their fear, except with reassuring thoughts about their first-use doctrine for nuclear weapons. In the long run, it won’t help. Russia is too poor and too corrupt to resist China’s money. There will be a “second government”, like the one alluded to by Joe Valachi, which will become the first government.

But that is not the Kremlin’s immediate concern, which is the dire absence in Russia of anything resembling industrial development, in a country where the 2013 male life expectancy is 65.1 years. Partly as a result of sanctions,  mounting disapproval threatens survival of  the Kremlin leadership.

Atavism has an unfortunate, continuing relevance for international relations. Two cavemen with clubs could have the notions that follow. Business suits and ties make it  harder to see.

Due to Western sanctions, the Kremlin finds itself dependent for investment on the country that could conceivably replace it with a Beijing-based power structure. One has only to look at the colonial exploitation of China for the mechanics. Between nations, fear is usually symmetrically opposed by fear. Russia needs to convince China that they don’t want to do to China what China would like to do to Russia.

Hence the naval demonstration, a metaphorical brandishing of a spiked caveman’s club, a way of saying, “Russia will not stab you in the back if you have a fight with the U.S.”  The corresponding guarantee, that China will not take back Vladivostok, is not forthcoming. It’s just a matter of time.