[quote=Ampharos]
And why not? You are a native of Siberia or a political opponent of the Russian Empire. China and Japan come invading with the intent of kicking Russia out of the region, and what are you going to do? Probably, you're not going to do anything, but you're certainly more likely to support China and Japan over Russia simply because they're the enemy of your enemy.
[/quote]

Nah. Japan and China have almost nothing to offer the people of Siberia. They risk too much siding with them, to earn nothing. As So Boerd said, most of the population is Slavic and much more likely to side with their government.