Why did the Soviet Union order the building of the Berlin Wall? The Kennedy Years 1961-1963

The
Soviet Union built the Berlin Wall separating communist East Germany from democratic West
Germany because the fence they erected was not doing its job.  Yes, it started as a fence and
over time became a wall. The Soviet Union's offical reason was that it wanted its borders
identified, and to guard against intruders. The greatof their offical reason was that  intruders
trying to get in was not the problem, the problem was trying to keep people on "their"
side of the wall.