This is a major milestone in Russian-Chinese military ties. China has taken part in numerous Russia-organized military drills before, but not in a major "strategic-level" exercise like this one
Via Alexander Gabuev.
Incidentally, Gabuev has long been skeptical about the possibility of a strong Russia-China relationship, especially on account of Russia’s weak understanding of China (see my article on The State of Russian Sinology, where I cover his arguments). So it means something when he says that China and Russia are moving closer to each other than at any other time since the 1950s.
Source: The Unz Review