by Jonah Shepp
A 2007 interview with Adi Ignatius offers a clue:
Putin argued then, as now, that the United States was on dangerous ground in its approach toward Ukraine. “The United States somehow decided that part of the political elite in Ukraine is pro-American and part is pro-Russian, and they decided to support the ones they considered pro-American,” he said. “We believe this is a mistake.”
He gave voice to the motivation that drives him now in Ukraine (beyond, of course, the possibility of extending Russian influence and perhaps territory). The breakup of the Soviet Union, in his view, was hasty and ill-conceived, and it cut off many ethnic Russians from mother Russia. He seemed to be testing an argument for the irredentist push Russia is now pursuing in Crimea and eastern Ukraine. “What did the collapse of the Soviet Union mean?” he asked. “Twenty-five million Soviet citizens who were ethnic Russians found themselves beyond the borders of new Russia. Nobody gave a thought to them. Is it not a tragedy?”
But Lucian Kim believes Putin’s true concerns are his own grip on power and his paranoid attitude toward the West:
Convinced that the new authorities in Kiev will finally pull Ukraine out of Russia’s orbit, Putin is hacking off as much of the country as he thinks he can get away with. He doesn’t want to re-create the Soviet Union as much as form a ring of buffer territories to ward off Western influence from the Russian heartland. For Putin, it’s the beginning of the endgame for his regime’s survival.
As Michael Totten sees it, the Ukraine debacle is all about checking the expansion of NATO:
What he most fears is that Ukraine might join NATO, removing yet another buffer state between himself and the West and kiboshing his plans for the Eurasian Union, a euphemism for a 21st century Russian empire. (Does anyone seriously believe Kazakhstan will be an equal partner with Moscow?)
Keeping his former Ukrainian vassal out of NATO will be easy now even if a militant anti-Russian firebrand comes to power in Kiev. The Crimean referendum—whether it was free and fair or rigged is no matter—creates a disputed territory conflict that will never be resolved in Ukraine’s favor. It will freeze and fester indefinitely. There isn’t a chance that NATO would accept a member that has a disputed territory conflict with Russia. No chance at all. Ukraine is as isolated as it could possibly be from the West without getting re-absorbed into Russia entirely.
Putin did the same thing to Georgia in 2008 when he lopped off the regions of South Ossetia and Abkhazia, and he did it for the same reason.
Joshua Tucker offers another explanation:
Numerous commentators have stressed the potential short-term and long-term economic and political costs to Russia of annexing Crimea and/or an extended military conflict with Ukraine (see in particular this commentary by Sergei Guriev and this one by Samuel Greene). So perhaps the simplest answer to this question is that whatever the economic costs, the Russian leadership has become convinced that doing nothing after ousted Ukrainian president Viktor Yanukovych fled Ukraine represented a security threat that could not be ignored. This could have been due to a very specific calculation, such as the belief that there was a credible threat to the future of the Russian Black Sea Fleet based in Crimea, or it could have been due to a more general concern that allowing Russia’s ally — Yanukovych — to fall without a response would signify weakness moving forward. Either way, the key distinction of this explanation is that Russia’s moves were essentially reactive in nature to a perceived security threat.