Unsurprisingly, the EU has been relatively quiet on this matter. The pressure from several of the older members - especially Germany - to keep Russia happy has led to a shameful silence when it comes to the security of the EU's eastern frontiers and neighbours. Our ongoing dependence on Russian gas, as well as the sluggishness of the EU's response to any Russian aggression aimed at the member and candidate states on their periphery, is directly as a result of the EU's failure to directly confront Moscow.
A belligerent line would, of course, lead to relations cooling rapidly. Moscow is still seeking to secure itself in a world so recently turned on its' head, and would not take kindly to future EU expansion eastwards. Yet these are important states - both in terms of resources, but also in terms of spreading democracy. The EU should offer membership to these states - on the normal tough entry criteria, yes - but membership. To snatch Ukraine, Georgia, Armenia and even Azerbaijan from under the nose of the Russian government would be intolerable to the Kremlin and a public relations coup for the EU.
The EU also needs to actively, and aggressively, seek out new sources of energy. A major nuclear power plant building programme, coupled with seeking gas routes and sources that avoid Russia altogether will be a good place to start. A more guarded approach to investing in Russia - which has already shown that it will interfere in foreign investments there for political gain - will certainly benefit the EU. We need Russian gas to keep the lights on - but Russia needs EU cash to keep pensions paid, tanks fuelled and all the rest of it.
But this line need not be adopted instantly. The EU should press on Russia in other ways - open up and fill it up with European cash and ideas. The soft power of the EU should be squeezed in wherever possible, and allowed to gently change the way Russia views the world. A good way to start would be to encourage European companies to buy whatever they can in Russia, and tie it inexorably to their new European owners. With cash locked up there, EU governments will sit up and take notice when trouble threatens, and will find it easier to influence Russian leaders.