Berlin remained the last open crossing inside the more and more militarised and airtight "inner-German" border. On 13 August 1961, the East German (GDR) leadership shut the border just weeks soon after East German leader Walter Ulbricht mentioned within a push conference "Niemand hat die Absicht eine Mauer zu errichten" https://israelpwbgk.hamachiwiki.com/971861/the_basic_principles_of_rum_tasting_berlin