How come in the last mission you are fighting Russians if they are on your side in the war? Also why are there no good mods?

NVM Misread your post. :D

OOOOPS :P

What is the reason?

My bad, I thought you meant "with the Russians". I totally had a brain fart. :P I evidently need glasses. :P

I guess every side wanted really bad those documents with the bank accounts and they were willing to do anything to get their hands on.

UK/US and USSR were allies only for the sake of defeating Germany, but they would gladly sabotage each other given the chance of not being caught.