China's communists take pride in restoring China from their nadir of humiliation at the hands of the Europeans. Western enclaves in China's ports where Western law was supreme and actual formal loss of territory to Europeans like at Macao and Hong Kong added to the pain.
But China has regained control of their coasts, including the former colonies. China has no actual territorial disputes with America or Europe.
That is not the case with Russia, the last European state to control territory seized from China when it was weak. China isn't shy about claiming other land. Why would Russia be the exception?
Is it really out of line for me to speculate--especially after their military redistrict reorganization--that China might really think of Russia as their prime military target?
UPDATE: The Russians really need to end their pointless provocations aimed at the West:
Military strength is now less than two million [Chinese troops]. This has not gone unnoticed in Russia, although there the state controlled mass media maintains a strict silence about how the Chinese military is not only twice the size of Russian forces, but has far more modern equipment, both in terms of quality and quantity. China also had a defense budget that is more double what Russia can afford. This also means that the in the Russian-Chinese relationship China is now the senior partner, in both economic and military terms. Russia is no longer an ally of China but a client state, dependent on Chinese goodwill and financial aid. China has also not mentioned the claims on most Russian territory bordering the Pacific and Mongolia. China never renounced these claims and occasionally mentions them (quite bluntly in the 1940s, 50s and 70s and more frequently but discreetly since the 1980s.)
Although honestly, I think Russia's bluster aimed at NATO, Sweden, and Finland--plus actual violence aimed at Georgia and Ukraine--is all about concealing Russian appeasement of China.