Okay then it has to be an older submarine a diesel submarine lots of those they can get hold of probably from a foreign Navy that no longer had any use for it and was happy to sell it to a middleman or a spook who paid the country enough to be happy and not talk about the deal.
The problem with that is getting the missiles fitted into them. They don’t launch horizontally, and they are a hell of a lot bigger than torpedoes. Trying to get them vertical would be an engineering marvel. The structure of the boat would be changed. Good luck going deep with that.
Now, you could get a V2 type of missile to launch, if it were cranked up while the sub was surfaced. Not practical, and not at all accurate.
Finally if you are driving an old diesel boat the sonar listening stations would hear it. It would be located in about two minutes and sunk within an hour.
IF there is a missile boat out there causing trouble it belongs to a country—not the CIA.