Modern Warfare 3 why are the soviets attacking New York?

Question

I just started playing MW3

I watched the intro movie

but I still dont understand

what is the reason the Russians are attacking America?

Answer 1

In modern warfare 2, you play as an army ranger turned CIA Operative, joseph Allen, Makarov (The main bad guy) in MW2/3 sets it up so that it looks like the CIA massacre an entire airport full of civilians and security personnel, making the russians think America attacked them, causing them to invade.

 

Source - Completed all MW games