NATO works because the Brit-Europeans are surrounded by 2 800lb Gorillas - the "good" Gorilla of the US and the "bad" Gorilla of the USSR*.
That describes the situation correctly from the days when Eu was in post-war ruins. This includes the post-fall of the wall period which in some Eastern European countries was actually worse than the post-WW2 recession.
Economically, the tables are now in a position where you have: 18.57Tn Gorilla, 20Tn Gorilla in the center and a 1.28 Tn Minnow. If we do the math for EEA, not Eu we are looking at even more - 24Tn+ gorilla. One _WITHOUT_ a drug, sorry debt addiction problem which has the economical power to create the military resources it needs and when it needs them.
By the way, Russia today is a very different beast from either USSR or its preceding Russian empire. Using the old USSR values in the equations yields the wrong results - they will _NOT_ react the same way USSR (or the Russian Empire for that matter) would have reacted under the same circumstances. That, however is a very different story and is offtopic for this discussion.