Tensions between East and West Germany were reduced in the late 1960s by Chancellor Willy Brandt's . In 1989, Hungary decided to dismantle the Iron Curtain and open its border with Austria, causing the emigration of thousands of East Germans to West Germany via Hungary and Austria. This had devastating effects on the GDR, where regular mass demonstrations received increasing support. In an effort to help retain East Germany as a state, the East German authorities eased border restrictions, but this actually led to an acceleration of the  reform process culminating in the ''Two Plus Four Treaty'' under which Germany regained full sovereignty. This permitted German reunification on 3 October 1990, with the accession of the five re-established states of the former GDR. The fall of the Wall in 1989 became a symbol of the Fall of Communism, the Dissolution of the Soviet Union, German Reunification and .