Russia isn't expansionist mate, but what it will do is respond to perceived threats, countries like the Ukraine form a wanted buffer for Russia between the Russian homeland and NATO countries and until NATO/USA start interfering and effectively poking the bear so to speak then nothing will or would have happened, economically going back into old soviet block countries makes no sense, take for example the Ukraine - it has little in the way of natural resources, is saddled with debt and its energy has been massively subsidised by Russia for the past 25 years, economically, politically and militarily it makes no sense to 'take it back'
Take the Crimea as a case in this, the Crimea is Russia's black fleet port, without access to it their screwed as it is a vital area for them to have access to, the area was until the 50's actually part of Russia not Ukraine until given away by Khrushchev - who was very pro Ukrainian having been raised their (many reports have him as being Ukrainian although that's questionable), the people to the large extent are ethnically Russian, they speak Russian, they have family in Russia, many of their parents or grandparents were born n Crimea when it was Russia.
If the EU/USA/IMF/NATO, would not have started to interfere in the Ukraine this entire situation would not have occurred, the biggest provocation was the knowledge that after the Ukraine overthrow the inclusion into NATO was just a matter of time.
Basically imagine Americas reaction to soviet arms and missiles being allowed to be parked right on their doorstep, sure as [Poor language removed] it would not be to meekly accept this, a case in point being the Cuban Missile Crisis.
Did that mean that after the USA got what they wanted that they then proceeded to invade Cuba, well no, because it had the desired result. What Russia is doing right now, is to draw the line in the sand, preventing any further NATO inclusion of former soviet countries, which frankly is perfectly understandable, NATO was set up effectively to guard or wage war upon Russia, theirs an obvious contradiction in whilst America and the EU refer to Russia until recent events as a 'partner' they at the same time are pushing military forces onto the borders of Russia, into former soviet countries, all the whilst acting surprised that Russia is becoming more alarmed at this encroachment.
Why is their a need to push more Military strength towards a supposed economic partner, some might say 'but look at Georgia', or 'Look at Crimea' as reasons why this is needed and good strategy, without actually realising that's its an absurd statement and illogical, its like pushing someone and when they push back, you turning around and saying 'well that's why we pushed them - we knew they wanted to push us all along'
Without NATO/USA encroachment and frankly manipulation of those countries then the Russian reaction never would have occurred.