There is no doubt in my mind that Peter Sellers made this movie. And what a movie!
Sellers plays several characters in this film, Group Captain Lionel Mandrake, President Merkin Muffley and of course Dr. Strangelove. Each not only showed an amazing command of various accents, English, American and German in that order; but highlighted just exactly why Seller's was one of the greatest character actors of all time. His gestures and traits change so much between characters; you often forget it's the same man.
Strangelove is played so over the top, crazed hair style, wide eyed stares, a precise german accent and alien hand syndrome, that occassionally makes a nazi salute. This is perfectly juxtaposed by the subtle and understated way, Sellers plays the President. A quiet man, unassured and stammering; who addresses the President of Russia; as if it were his wife. Even with a looming nuclear disater, he is played down. The whole film is a master of satire; hysterically funny in places and very fun in the rest.
Kubrick, the master of controversy; makes a really unsettling case and point in this film; about our fragile position on this earth with advancements in nuclear weapons and wartime frictions. I cannot imagine how much more unsettling it would have seemed at the time; as it arrived right in the centre of the cold war.