Ping!
It is very hard for me to believe that Putin and Russia are the modern day equivalent of the former Soviet Union.
I don't see the political and cultural will that is necessary for Russia to be an aggressive, expansionist, great power.
Bottom Line...
Putin needs a warm water port - thus, the Crimea and Ukraine issue.
Second, he has many potentially dangerous neighbors - Erdogan in Turkey, Iran, various Islamic groups, a currently neutral India, China (which dreams of a new empire), and a nuclear armed psychopath in North Korea.
To my eye, Putin is much more pragmatic than dangerous.