The reason of the wall separation (source a & b) The Soviets &the East Germans built the wall to stop the immigration of the GDR citizens to the GFR ( German Federal Republic).
Between 1949 & 1961, around threemillion people crossed the border to live in West Germany. The defectors were mainly part of the elites (intellectual, artists, but working class elite as well). Itgave a bad image of the GDR, which was supposed to be the paradise of the working class.
The use of the wall by the Americans propaganda (Ich bin einBerliner, JFK, West Berlin, 26 JUNE 1963) Kennedy uses Berlin as an example, to denounce the communist system. He delivered this speech in front ofthe population of West Berlin, but he addressed the whole “free world” ( the western block). He denounce first the “fifth column” in the Western bloc (peoplewho says that communism can improve the world).
→ He challenges them to come to Berlin to see with their eyes the situation created by the communists.Kennedy accuses the communists of crime against humanity, because they divided families & the Berliners into two antagonist sides.
Berlin & the wall became asymbol of the communist oppression. This symbol lasted for the whole cold War until its fall of 1989.
Conclusion : The wall became a physical division ofthe city of Berlin, but more it became a mental separation between East & West. The West used this for its propaganda against the communism & communist world .