In what ways does Kennedy use the building of the Berlin Wall as a propaganda weapon against the USSR?

The Berlin Wall was often seen as a physical representation of the "Iron Curtain" that had descended over Europe/the world at that time. Kennedy uses the wall as an example of what Communism does to its people and the physical barrier or separation between those people. He compares those living on either side of the wall and their quality of life and shows how Capitalist Berlin is prospering and growing economically while Communist Berlin is closed off and is not progressing economically.