By who?
Are you suggesting the combined European armies could repel the Russian Army?
Not likely.
The numbers mismatch would dictate the outcome. Not only that, there is not much technology gap between what the Russian forces have in the field, and what Germany has in the field.
Puhllease, the Russian army is just as corrupt and incompetent as it has always been.
They are good at hand building a few decent pieces of equipment for select units: the rest is junk. To say nothing of their extensive infantry training building dachas for the officer corps.
This article from Polish newspaper claims Russia has already suffered 2,000 KIA fighting in Ukraine. link
Sounds high to me, but probably not by much.
And that was fighting the Ukrainian army and irregulars.