Guerrilla war in eastern Ukraine is next but this start of WWIII.
I’d say on the Timeline it’s 1938.
WWIII is already underway, but because it is not likely to be similar to WWII with well-defined front lines, we don’t think of it as a global war.
Typical for the new warfare will be wide use of terror and guerrilla tactics. Civilian population will be used routinely as shields or as provocation fodder.
For example, the pro-Russian insurgents would deliberately set machine gun nests in apartment blocks, with the hapless residents still in them. That way if the regular army holds the fire trying to spare civilian lives, they get a military advantage, and if the regulars hit the building they get a propaganda advantage to elicit more Russian aid. When the Ukrainian army is not close enough for them to engage it they would deploy a squad of mortars, shell their own territory and quickly disappear, creating another story how the Ukies kill civilians.
The civilized nations will fight at a distance, with drones and from aircraft carriers, in order to shift the balance of power on the ground.
That is the face of the new war. We saw it in Chechnya, Lebanon, Iraq, Libya and Syria and now we see it in Ukraine.
Guerilla warriors need a sympathetic population in which to operate. One of the worst assumptions here is that the whole of Ukraine is united and in favor of the govt in Kiev. At best the majority is indifferent.
We see the same false assumption (wishful thinking) when it comes to supporting rebels in Syria or Libya or wherever. We assume everyone in these fractured countries is of one mind or that all the rebels share the same ideologies and loyalties.