Buy gold. Lots of it.

The Russian occupation of Crimea has challenged Mr. Obama as has no other international crisis, and at its heart, the advice seemed to pose the same question: Is Mr. Obama tough enough to take on the former K.G.B. colonel in the Kremlin? It is no easy task. Chancellor Angela Merkel of Germany told Mr. Obama by telephone on Sunday that after speaking with Mr. Putin she was not sure he was in touch with reality, people briefed on the call said. “In another world,” she said.

I don’t think she means he’s had a mental break, I think probably she means that he’s starting to believe his own BS about the Kiev uprising being an American-backed plot and the Euromaidan protests being driven by Nazis. My assumption, like yours, is that Moscow pushes propaganda like that knowing full well that it’s false yet irresistible as a fig leaf for invasion. Merkel’s comment raises the possibility that Putin really has talked himself into believing that Ukraine is ground zero for some next-gen Nazi assault on Russia. That’s one way to explain his otherwise inexplicable invasion of Crimea. No one was threatening Russia’s naval base in Sevastopol; if the new Ukrainian government had been stupid enough to try to boot Russia off the peninsula, Putin would have rolled right over them. Invading Crimea preemptively makes sense only if he’s convinced himself, against all available evidence, that the ethnic Russian majority there — and in eastern Ukraine — is genuinely under threat from rampaging CIA-backed Ukrainian fascists.

Alternate non-crazy explanation for the invasion: He did it simply because he can.

Because he can. That’s it, that’s all you need to know. The situation in Kiev—in which people representing one half of the country (the Ukrainian-speaking west) took power to some extent at the expense of the Russian-speaking east—created the perfect opportunity for Moscow to divide and conquer…

Russia, or, more accurately, Putin, sees the world according to his own logic, and the logic goes like this: it is better to be feared than loved, it is better to be overly strong than to risk appearing weak, and Russia was, is, and will be an empire with an eternal appetite for expansion. And it will gather whatever spurious reasons it needs to insulate itself territorially from what it still perceives to be a large and growing NATO threat. Trying to harness Russia with our own logic just makes us miss Putin’s next steps.

To spin that out a little, maybe Putin feared (rightly or wrongly, probably wrongly) that the EU would put together a big aid package for the new Ukrainian government. As the country stabilized and the economy improved, even Russian strongholds in the east and in Crimea would take a second look at closer ties with the EU. Once that happens, Putin’s in trouble at home from Russians who want a taste of the same thing. “If Ukraine’s a success, a smooth transition, a nice government, doing nice reforms—for Putin, it’s the end of him,” said former Georgia prez Mikheil Saakashvili to the Journal this weekend. By squatting on Crimea and eastern Ukraine now, he’s making sure that there’ll be no western tilt in his buffer zone.

That’s a more rational explanation for invasion, but that has problems too. Managing Crimea, with its large Tatar minority and its dependence on northern Ukraine for power in the short-term, is a potential headache. And if he’s ultimately worried about unrest in Russia itself, the economic warfare that might be waged on him by the west (assuming Eurocrats aren’t too greedy to cut off easy Russian money) in retaliation for invading may carry more risk than staying out of Ukraine would have. Despite his reputation for 10-dimensional chess-playing, this guy does miscalculate: Kevin Drum is right that the reason we’ve reached this moment in the first place is because Putin and Yanukovych fumbled the country away. They would have preferred to short-circuit Ukraine’s flirtation with the EU through bribes, aid packages, and other below-the-radar measures that didn’t involve western sanctions. They’re landing troops now because Putin needs to show the natives that he’s still in control after a humiliating loss of control. Or, alternatively, because he’s nuts, of course.

Merkel and Obama are trying to give him a way to back down while saving face by letting western observers enter Crimea to see if there really are packs of wild Nazis staging pogroms against innocent Russians there. Will Putin go for it? Hmmmmm.

Update: You know, I don’t either.