As the Soviet Ambassador, Alexei de Sadeski is the only real live "Commie" we meet in Dr. Strangelove, making him the movie's representative of the entire Soviet enterprise. Well, he is an ambassador, so that's kind of his job. Alexei is a proud card-carrying Communist and makes it clear from the first moment he enters the War Room, when he demands Cuban cigars over Jamaican ones, saying,
DESADESKI: I do not support the work of imperialist stooges. (Cuba was Communist and Jamaica was part of the British Empire.)
Notice that "De Sade" is ingeniously hidden inside the Ambassador's name. Even the Russians aren't immune to Kubrick's sexual innuendo.
The total absurdity of U.S./U.S.S.R tensions is captured when, shortly after making his grand entrance into the War Room, Alexei gets in a wrestling match with General Turgidson, claiming that Turgidson tried to plant a spy camera disguised as a book of matches on him. The tussle has to be broken up by the President, himself, who does so with one of the most famous lines in the movie:
MUFFLEY: Gentlemen, you can't fight in here. This is the War Room!
Though he's rather full of himself, Alexei actually ends up being the one of the more sensible characters in the whole movie. When his boss Premier Kissov tells him about the Doomsday Machine, he doesn't think it's cool at all, even calling people in his own government "mad fools" and suggests that he fought against the idea.
In the end, though, it seems that Turgidson's suspicions about Alexei were correct. The last time we see the Ambassador, he's secretly taking pictures of the War Room's big board with a camera disguised as a pocket watch. Of course, this is after Turgidson has already started the ridiculous conversation about closing "the mineshaft gap" with the Soviets. It's clear that, despite ending most life on Earth, the U.S and the U.S.S.R. still haven't learned their lessons.