Americans are bloodthirsty because outside of the Civil War, they've never had to face a real conflict. Saying "Bomb them to hell" is a socially acceptable way to express all their petty frustrations without any real consequences. Russians are an acceptable threat for bloodlust because they're "white" (not everyone who lives in Russia is even ethnically Russian or white...) and Russia is an eternal threat for the Angloid Atlantic establishment (despotic hordes from the East!) despite the fact that Russians have generally had a pretty friendly view toward the US when Yankees weren't trying to pound them into dust.