The Russians aren't alone in producing man portable nukes. The US version, was to be carried into places like East Berlin by Delta troops that were stationed in West Berlin. They had a life expectancy of 48 hours of exposure to the manpack before the radiation would kill them.
Simple mission: Avoid capture and get into position, then sit down and begin the arming seuence. If arming sequence not completed within 48 hours, auto detonation. Weight of manpack reportedly 85 pounds, and resembled a standard ALICE pack (Mountain). Those assigned this mission had no time nor desire to get away after the arming sequence - they knew that their lives were done after carrying it so long.
I personally knew alot of the plans for the defense of Berlin and I must say that I do not agree with your statement. Delta in Berlin is one of those areas that was somewhat unclear (sometimes they were there ... sometimes not .... if I was to bet nukes were NOT a primary mission .... being staged forward for hostage rescue seemed to be their primary job ... ). I also knew some ADM guys and Delta clearly did not have a "monopoly" in that area back then. Most of the "spy stuff" was done by the Potsdam Liaison Mission (going into East Germany) and the Field Stations. Potsdam would have been a FAR BETTER choice for your stated believed mission then Delta. I knew one guy who had over 160+ successful missions (at least that what he claimed after a couple of beers ... he was a Scout PS in the Berlin Brigade when I was a Company Commander there) into the east and had several cars shot to pieces. They knew where and how the get into the East legally and illegally (although that was not too hard ...)