What was the main point of disagreement regarding the berlin crisis in 1961?

Berlin Crisis was the last and final major incident of Cold War. This Cold War talks about the status of Berlin and post-World War II Germany. The main point of disagreement happened between West and East Germany is about the East Germany's brain draining to West Germany's younger educated professionals. More East Germany people migrated to West Germany. The Soviet Union gave an ultimatum regarding the withdrawal of Allied Forces from West Berlin.

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast.