Garry Kasparov has made the following Tweets:
The reason to take difficult & dangerous steps to stop Putin today is simple. It will get more difficult and more dangerous tomorrow
The Russian commanders think Putin is crazy but he keeps being right, keeps winning without resistance. So they follow. It's 1938-39 again.
The most dangerous element is Putin & his followers' sense of invincibility. The longer they go unopposed the harder will be to stop them.
Obama & EU kept looking for easy & safe ways to fight Putin. They refused to make tough decisions and the price always keeps going up.
Putin is probably trying to calculate what's the most he can take consistent with keeping the probability of a major war with the United States below some level. If the U.S. is unwilling to fight, Putin will take all of the territory of the Soviet Empire + perhaps Finland, a country that used to belong to Russia.
Putin probably knows he might have a limited time to act because the U.S. might get a hawkish President (Hillary Clinton, any Republican but Rand Paul) or Germany might re-militarize.
Some of the comments on the link by James_Miller exactly six months ago provided very specific estimates of how the events might turn out:
James_Miller:
Me:
"Russians intervening militarily" could be anything from posturing to weapon shipments to a surgical strike to a Czechoslovakia-style tank-roll or Afghanistan invasion. My guess that the odds of the latter is below 5%.
A bet between James_Miller and solipsist:
I will bet you $20 U.S. (mine) vs $100 (yours) that Russian tanks will be involved in combat in the Ukraine within 60 days. So in 60 days I will pay you $20 if I lose the bet, but you pay me $100 if I win.
While it is hard to do any meaningful calibration based on a single event, there must be lessons to learn from it. Given that Russian armored columns are said to capture key Ukrainian towns today, the first part of James_Miller's prediction has come true, even if it took 3 times longer than he estimated.
Note that even the most pessimistic person in that conversation (James) was probably too optimistic. My estimate of 5% appears way too low in retrospect, and I would probably bump it to 50% for a similar event in the future.
Now, given that the first prediction came true, how would one reevaluate the odds of the two further escalations he listed? I still feel that there is no way there will be a "conventional battle" between Russia and NATO, but having just been proven wrong makes me doubt my assumptions. If anything, maybe I should give more weight to what James_Miller (or at least Dan Carlin) has to say on the issue. And if I had any skin in the game, I would probably be even more cautious.