True fans of the Dr. Strangelove movie would certainly remember this exchange between Dr. Strangelove and the Russian ambassador:
Dr. Strangelove: Of course, the whole point of a Doomsday Machine is lost, if you *keep* it a *secret*! Why didn't you tell the world, EH?
Ambassador de Sadesky: It was to be announced at the Party Congress on Monday. As you know, the Premier loves surprises.
I doubt Dr. Strangelove was a required movie-watching experience for Soviet military planners, but they got the point (we should thank Stanley Kubrick for making it so well in the movie). Here is a copy of an internal Central Committee document from 1985, which discusses various ways to increase effectiveness of the Soviet strategic forces. The author, Oleg Belyakov, head of the Military Industry Department of the Central Committee, complains, among other things, that
No [adequate] attention has been paid to a proposal, extremely important from the military and political point of view, to create a fully automated retaliatory strike system that would be activated from the top command levels in a moment of a crisis
This is exactly a Doomsday Machine that he is describing. The true Strangelovian moment comes at the end of the sentence quoted above -- the author adds, in parenthesis
(with a notification to the adversary).
Of course, the whole point of a Doomsday Machine is lost if you keep it a secret!
The Soviet Union never built this automatic Doomsday Machine (also known as Dead Hand) -- the Perimeter communication system that is often mistaken for it is something quite different. So we will never know, had that system been built, would the Soviet leadership have waited till a Party Congress to make the announcement?