So MW2 did invoke NATO's mutual defence treaty and therefore draw Europe into Russia's pointless war Red Dawn revival with the USA? Wow, this somehow makes MW2's campaign even moar dumberer. So now Russia has to fight the USA (the world's strongest military), but also the UK's, France's and Germany's (all of which are within the top 10 militaries in the world) too? Russia might have enough manpower to fight the USA head to head on a single front, but add in another 20+ countries on the other front and now you've got a completely foreseeable no-win situation. In fact, this no-win situation was the exact purpose of NATO in the first place (making it too hard for Russia to fight a land battle against the West)!
Did they learn their history only from Cold War era action movies? ... Wait, don't answer that. It'd be one thing if they weren't trying to be serious (see Bad Company 1), I'd let it slide then, but CoD is about "t3h r34l15m 4 t3h w1n", so I know they won't even try to make this funny (however it may turn out that way unintentionally).
AGGHH! This plot is going to be so stupid it hurts isn't it? Yeah, I thought so. I'll be in BF3 in anyone needs me.