My personal speculation is that Putin won't push Russian troops into the rest of Ukraine (beyond Russian/Russophone-majority areas), simply because there isn't much reason for him to do so. Establishing a pro-Russian government in the areas that have been occupied will be sufficient for him to be the Big Man on Campus.
And, frankly, there's not much the US or NATO or the EU or the UN can or will do about it, aside from waggle their fingers and make other symbolic gestures. Not only is Western Europe highly dependent on Russian petroleum and natural gas, but unless the whole thing devolves into another Yugoslavia, there's not enough of a sense of moral outrage to justify (or grease the wheels) toward war.
A bigger issue is what Putin might be inclined to do next with others of his neighbors. And the answer might be, well, it depends on whether those neighbors seem to disrespect Russia or threaten to turn to the West, despite the example Russia's now set in Georgia and Ukraine.
Reshared post from +Yonatan Zunger
The top story in the NYT right now (http://nyti.ms/1eK5q67).
This very distantly reminds me of the day when the USSR started to mass its tanks on the borders of Latvia, Lithuania, and Estonia — in the heady days of Glasnost, they had started talking about independence, and as the army began to assemble, we all wondered, was the new openness of the past four years a dream? A fake? Would ideas of freedom or change be crushed the way Hungary was, the way Czechoslovakia was?
But that was a very different time — days of promise and openness, and profound uncertainty mixed with hope. That tension was swept away in the torrent when the Berlin Wall came down, so suddenly and unexpectedly, and Lech Wałęsa came out and suggested that this would be a good time for Poland to have elections and the world became unrecognizable overnight.
This is almost nothing like that. In real historical terms, it's more similar to the perpetual border questions between Armenia and Azerbaijan, or with South Ossetia, nestled between Georgia and Russia. Ukraine is profoundly demographically split, in no small part due to Stalin's habit of picking up ethnic groups and moving them around to create precisely this sort of situation: lands previously independent of Russia, now with large Russian populations that have every reason to actively want to remain part of the USSR and under Russian control. And all of the struggles in Ukraine ever since the USSR was shut down live in this shadow.
Now Yanukovich has fled — in Russia but far from Moscow, kept in Putin's reserve, in effect, in case it becomes useful to reinstall him somewhere — and a new government in Ukraine is clearly anti-Russian, likely to want to ally themselves more closely with Europe: Putin's great bugaboo. (How many times has Russia threatened to cut off countries' fuel supplies, shut down their economies, cause "trouble" for them, if they got too close to Europe? The gradual failure of the Warsaw Pact was perhaps the greatest blow to Russia's geopolitical power, in its day)
But even among the valuable sites of Ukraine, one stands out: the Crimean Peninsula, strategically located between the Black Sea and the Sea of Azov, site of so many critical battles in the past two centuries. It has had semi-autonomous power within the Ukraine nearly since that country's inception, something backed strongly by Russian force — since Stalin ensured that this area would be majority-Russian, forcibly deporting most of its population to central Asia in 1944.
And now Russia has, in effect, invaded it. Russia would like to take all of Ukraine, and make it Russian territory, no doubt, but it's quite possible that Putin considers it to be an acceptable second choice for Ukraine to split in half, with Russia taking over the Russian-speaking regions — which, not at all coincidentally, includes the entire Ukrainian coast.
This will not be pretty. It's not going to turn into World War III — nobody is insane enough to say "hey, let's start flinging nuclear weapons at each other!" over this — but it's a significant turnover in just how far Russia is willing to go to assert its control over the areas which it considers to be its natural sphere of influence. And that's going to have repercussions throughout the former Soviet world, and beyond.
A good map of the linguistic and cultural splits in Ukraine: http://www.businessinsider.com/this-map-explains-why-russia-is-invading-crimea-2014-3
A good map of oil pipelines which flow through Ukraine, another of the reasons why it's so strategically critical: http://www.zerohedge.com/news/2014-02-20/ukraine-situation-explained-one-map
Other key reasons being access to the Black Sea, its status as the major breadbasket of the Soviet world, and its strategic location for armies moving to and from the southwest.
From another Forum. One poster was sneering that Obama and Kerry were weak, and would let Russia do anything. When challenged at what he would do he responded
BTW – next time Chamberlain comes up, just think of the parallels.