- EU is basically the third largest economy in the World. Meanwhile, Russia is about similar size economy as Italy. The combined EU military spending and capability/equipment is well above Russia's. So, in terms of economic and military power, the EU certainly has means, but see below.
- Would EU have political might and unity? That is a big question. However, the situation with the Baltic States is not so simple: these countries are well integrated parts of the EU, including the membership in Eurozone, Schengen Area, financial and banking system (banks are mostly Scandinavian in the Baltics), etc. Any threats to them would have significant consequences e.g. to Euro as a currency.
- While some EU countries might be reluctant to do anything, there would be other EU countries which might take unilateral action as they might feel threatened too. In particular, Nordic countries and Poland (which, by the way, recently is getting very heavily armed).