For many years, the most accurate (paper) maps of the Soviet Union were those created by the CIA. The USSR's own maps included lots of intentionally incorrect data.
I remember from my childhood (early seventies is Soviet Union) that it was allowed to print road maps with straight lines only and distances between cities were always at least several kilometers wrong. I also remember when my classmate lost the map when orienteering (these were relatively accurate) and he and his parents had a lot of trouble because of that.
