China is, despite everything, a mostly-sane player with oodles of baggage on the world stage right now. The real problem is Putin and his associates in Russia who are more than nostalgic for the return of the 'glory days of the USSR' and are more than willing to basically turn the world to ashes to do so, aka Grade A nostalgia. It must be noted that nostalgia of that magnitude tends to attract the mostly-insane.
We'd all be better off if Putin and his inner circle were doing this purely for nostalgic reasons. The truth is far worse and far more dangerous. The truth is that ethnic Russians are dying. Their medical system collapsed with the Soviet Union, as did their apprenticeship programs. The younger demographics do not have the same number of engineers, scientists, and other skilled labor as what passes for their boomer generation does. And that generation is nearing the age of mortality (60s). And as they age not into the grave, the young generation that serves as their military personnel are going to be aging into their 30s and 40s.
The newfound Russian aggression is born not out of a desire for glory, but the desperation of oncoming death. Moscow's only hope is to expand its borders, because the borders that Russia has right now are horribly exposed to an invasion from the European plain. History has shown it through the Napoleonic Wars, WWI, and WWII that Europeans can and will invade from that direction. The only way the Russians can become secure in their geography is to move into linchpin states that they lost.
That means that if Russia is to truly be secure, they must secure the approaches to Russia. Most important are the European and Turkish approaches. By retaking Crimea, the Russians have secured one of the Turkish approaches. They have some security in Caucuses. If they want to be secure on the European front, then they must move to retake the states along the Baltic Sea Coast, as well as the space that runs down the Carpathian Mountain range, down to the Balkan Mountains.
And this is certainly a must for Russia now. The Ukraine incident impart assured that the Russians would approach the matter militarily. Russia could tolerate a neutral Ukraine so long as it paid homage to Moscow. It could not accept a Ukraine that was within the EU or NATO. Doing so would rob the Russians of Crimea and put you (just from Kiev)
within an 11 hour drive to Moscow. And from Sumy it's about 9 hours. We're talking about NATO bases being anywhere from 600 to 900 km away from Moscow.
At a conservative 900 km (from around Kiev), an F-15 could reach Moscow in 28.8 minutes. At 600 km, it could reach in 19.2 minutes. An F-35 could do it in 45 to 30 minutes respectively. And that doesn't include things like cruise missiles, ballistic missiles, and future hypersonic missiles. Of which would probably overwhelm even the Russian S-400 defense systems.
The West supporting the coup against the Russian-backed government gave Moscow little choice but to take half of Ukraine. Most importantly, it could be done with minimal effort and risk. A strong ethnic Russian population within the region, military assets already present in Crimea, and of course, unmarked troops could be used to bolster the willing population in eastern Ukraine. Germany and other EU states that relied upon Russian gas would be less willing to halt Russia's advance.
And the point was made clear;
this far and no further. The West has responded of course by fortifying western Ukraine, but how long that can hold is anyone's guess. With the economic downturn, the demographic downturn, and the sudden lack of American protection (not to mention markets), many European countries are going to think twice about putting the screws to Russian advancement.