I haven't heard anyone say this yet, but Russians lost a lot of money when the EU "bailed out" Cyprus by bailing it in. More to the point, the EU confiscated 40% of deposits in Cyprus banks in excess of 100,000 euros, which hit a lot of rich Russian depositors pretty hard. It was another example of EU overreach in the opinion of Russians, something of which the West has been very dismissive but which Putin has indicated will not fly anymore as early as 2008, and proved it when he annexed South Ossetia during the Olympic Games in China.
Crimea was a perfect opportunity for a little payback for Cyprus, considering that the US has been trying to push Ukraine into the arms of the EU, most recently when Senators John McCain and Chris Murphy visited Ukraine in December and threatened the country with sanctions if it did not ally with the West.
From Putin's perspective, the EU means losses for Russia. American policy isn't taking that seriously enough, because if it were Putin wouldn't need to resort to arms.
