China is probably not yet ready to mount a complex air-sea invasion of Taiwan, with the mighty USA at its back. But it would have no real difficulties making land invasion into Russia.
Taiwan… not yet, too hard, but Russia is officially a GO opines our dunk tank subject, further free military advice for China can be found in the article
Many Chinese (ultra)nationalists have long dreamed of retaking Vladivostok (Haishenwei), which is still one of the painful points along Sino-Russia relations and many see it as a great humiliation that must be avenged. The goal is to weaken Russia so much that eventually Russia has to cede Vladivostok back to China.
It will also cut Russia off from access to the Pacific (one of the most salient problems for both Russia and the USSR that have shaped their geopolitics in the Far East for more than a century) that could further subjugate Russia under China’s control.
This may not happen now but eventually China will want it back.
Don’t see anything like this happening unless there’s regime change in Moscow and Russia becomes a western puppet. On the contrary, it seems that cooperation in far eastern ports is what’s on the actual table.
Ultras are just being ultras.
Because some Chinese boomers cry about it,or is there a material reason you think so?