 Intriguingly, the personnel department of the SED attempted (without success) to block Gerstner's recruitment into the Soviet-sponsored "trade administration".They cited strong doubts over Gerstner's assertion that he had joined the Nazi Party back in 1933 only because he had been mandated to do so by a communist student organisation, and they speculated over a possible "connection" to the Soviet security services.Although the political differences implicit in the military and administrative division of Berlin since 1945 would, after 1949, be replicated by increasingly stark social, economic and eventually physical barriers, during the late 1940s Berliners could pass freely between "sectors", often with little reason to know where the frontiers were.