Unfortunately, there are parallels with the intial nazi expansions.
The good news is that comparison breaks down when you look at certain details...
The nazi's leveraged German military tradition, technical ingenuity, industrial base, and societal unrest to produce what was the finest military force in the west, and probably in the world.
Putin and russia can't afford to do that economically...and russian culture doesn't make it easy either.
The western powers were weak in the 1930's, and had mostly WW-I leftover hardware. The NATO powers may have smaller forces, and may be preoccupied in the middle-east, but we have VERY modern, state-of-the-art combat systems...and we are very good at employing them.
We have twice demonstrated our ability to rapidly and catastrophically overwhelm battle-hardened mechanized and armored forces which use soviet hardware, soviet training, and soviet doctrine...the eastern powers DEFINATELY took note of that in 1991 and 2003. The current chinese military build-up is believed to have been the direct result of the rapid collapse of Iraqi forces in the first gulf war. The chinese use the same equipment and doctrine and they were totally shocked when Iraq was rolled up in 100 hours...they would not have believed that possible before the war.
This time the blitzkrieg is OUR capability.