You have to be more clear. If you are afraid of Russian expansion, it did not happen in 49-89 and Russia is not the be blamed for it.
If you are talking about Communism expansion - it will not happen again as Communism is a dead ideology.
Russia has no means to expand into Central or Eastern Europe and will not have them for decades to come. The only thing that would force Russia into some form of conflict with those nations is their arming and training by the US. Solution is simple: keep the status quo.
Soviet Union was another mask for Russian imperialism. That's not completely true, but it is to some extent. Why do You think the most fierce russian nationalists glorify communism and Stalin? Because it's made a state using russian official language and having a capital in Moscow a global power.
Expansion is not just direct territorial gains, btw.
Russia has no means of expanding - but many of its citizens simply don't know about it. They live in horsehockey conditions, so they take proud at the vast territory of their country and possibility to bull other countries.
Russia is not a world power - but its authorities want to keep their citizen in conviction that it is, because it makes people support them. Perhaps they do believe it themselves, or will start believing it. And then we're in trouble. Russia may not have possibility of expansion, but it may still try to, and that means horrible consequences.
Even worse is people in the west accepting russian illusions of grandeur as a fact and admitting Russia has some "sphere of influence". It does not. Its influences are where they really exist - Belarus or eastern Ukraine is a sphere of influence of Russia, for example, but this shouldn't mean other powers can't play there as well, nor that Russia has right to intervene there directly.
Poland definitely is not a russian SoI, nor Czech Republic, simply because Russia has hardly any supporters here, mostly because of russian arrogrant policy in post-1989 years. Sympathy for Russia in poland is lower than in 1989. In Ukraine, for the first time in history polls show that majority of population doesn't trust Russia (something like 53:37, don't remember, exactly). If Russia tried to exert political influence by diplomatic means, it would have been more successful. More effective, but less spectacular. And Russia treats foreign policy as a means of controling internal one, just like Kaczynski brothers in Poland. More quarrels abroad = "we are defending Mother Russia against traitorous Ukrainians / perfidious Poles / nazi Georgians.