Okay, let me try to give ya a run down of the backstory or at leas some of it. Following another war in the middle east, the middle easts oil supply is pretty much done for, which affected America, and a few other countries which resulted in a crisis. Taking advantage of the situation, South Africa formed The Federation with a leader that was strongly anti american, to the point he ordered the deaths of any American found there.

Of course this painted them as an enemy to the US.

Without going into to many spoilers here, The Federation was able to smuggle a strike team onto ODIN (Which is based on an actualy weapon) and redirect it to fire it upon Southern United States, before we ( the player) are able to bring it down.

In all honesty, I love the campaign of this story, and think it is one of the better ones. I wasn't a big fan of the multiplayer.