You've got to watch it again. I never saw this before, but in the final scene where Strangelove's arm goes nuts, and Sellers is beating it, the Russian actor is trying hard to not laugh. He does laugh, but tries not to. I never noticed it before.
Sellers was great.
“Mein Feuhrer, I can walk!!”
I laughed myself silly at that final scene. Damn he was funny!
Peter Bull, the actor playing the Soviet ambassador, was actually British.