mitch johnson does not need a reenactment of the cold war. he was there as a sergeant at the time, one of 6000 gis stationed in berlin. >> at the same time we had our soldiers in the city, there were thousands and thousands of russians and east german troops on the other side. we were basically an island at inside of east germany at the time. there was always during the training time it was said war could break out. >> that was the reality for decades. at checkpoint charlie was the new front line where soviet and american tanks faced off in 1961 during the berlin crisis. now it is all part of a stage show, but that does not bother mitch johnson. >> this is very important that even though it has become more commercial, i think it is very important that is still here. that the kids who were growing up today, because they do not know about the cold war, that they'd see part of the history of the city they are living in. >> the real checkpoint charlie guard house is not in the city's southwest and allied museum. there's also a british cargo plane