There are hundreds of satellites in orbit worldwide, Leo and geo. You think they could hide the materiel to conduct this kind of warfare?
Ukraine was warned by the US leading up to the invasion. They just refused to believe it.
When the US declares there is risk and brings people home from Korea and Taiwan, and moves the fleet into region for more than freedom of the seas and wargames manoeuvres i will believe there is sonething here.
If you want a canary in the coalmine, look at Vietnam. There's no love lost. If they muscle up, something is happening.
Two of your proposed engagements would echo the iran-iraq conflict for body count because they will be contested on sea and land, and at great cost to the aggressor. The last time Korea was fought over approximately 5m troops were committed. I guess that soaks up a lot of china's unemployed youth but I doubt they will be happy about it.
There are no cheap victories here. Once the more modern stocks of weapons runs out, it's slings and arrows.
Henry Kissinger will fix it. Don't worry.
Russia doesn't want to rebuild the Soviet Union. They want to rebuild the Russian Empire. The Baltic countries, Finland, and (all of) Ukraine were parts of the Russian Empire and are more likely to be invaded that ex-USSR states like Armenia and Azerbaijan.
Putin sees himself as Peter the Great and not a "dirty little Georgian peasant" like Stalin.