This brain drain of people emigrating away from East Germany was causing a huge economic strain on the country. In order to curtail the massive exodus, the Russian army put up barbed wire fences to prevent crossings of the East German/West German border. Did you find the 3 changes? Click to see the next puzzle.
People wanting to flee found a loophole in which to escape. Rather than crossing at the East/West border, they would enter West Berlin and then they could fly anywhere in the world.