In the summer of 1989, the embassies of the Federal Republic of Germany in Prague, Budapest, Warsaw and the Diplomatic Mission in East Berlin were occupied by refugees from the GDR who wanted to force their emigration from the GDR in this way. The policies of Perestroika and Glasnost which had been introduced by the Soviet Party Leader and Head of State Mikhail Gorbachev and the political changes which were made possible due to this in Hungary had the effect that the state of the Balkans no longer accepted the common policies which were the pre-requisite of the treaty of friendship with the GDR, as a consequence annulled the treaty and opened the border to Austria for the refugees from the GDR.
This opening led to a mass flight into the Federal Republic of Germany. After the GDR finally gave in, the refugees from the embassies in Prague and Warsaw were also allowed to emigrate into the West. In September 1989 alone, 15 000 citizens of the GDR emigrated to the Federal Republic Germany.
With the fall of the Berlin Wall (9/11/1989), the public discussion - on a national and international level - regarding the question of a unified German state, in its historical-political problem setting as well as in every other respect, increasingly moved into the centre of attention. The prime minister of the GDR, Hans Modrow, demanded a contractual association as goal of a German-German co-operation. On the basis of these conceptions, the Federal Chancellor Helmut Kohl drew up a ten-point plan (28/11/1989), according to which the German unification was intended to be achieved by way of a confederation. The open borders, the economic differences and the crumbling power structures promoted the wish for a rapid German unification amongst the demonstrating citizens in the GDR. For the conservative-liberal coalition which was in power at the time in the Federal Republic of Germany, a rapid unification was more or less elevated to its foremost policy of the government. The government of a large coalition under prime minister Lothar de Maizière which had resulted from the first free election in the GDR (18/3/1990) also strove for a rapid reunification.
In a state treaty between the Federal Republic of Germany and the GDR (which came into force on 1/7/1990), the principles of a reunification of the two states was agreed, especially in form of an economic, monetary and social union. (Introduction of the Deutsch Mark as legal tender in the GDR on 1/7/1990.) After fierce controversies, the Lower House of Parliament voted in favour of the reunification treaty which had been negotiated between the governments of the GDR and the Federal Republic of Germany in September 1990 on 20/9/1990, so that the reunification could come into force on 3/10/1990.
The German-German reunification process was accompanied by negotiations of the four superpowers and the two German states (2+4 negotiations), in order to achieve an inclusion in a European security concept.
Poland demanded to be able to take part in the negotiations because its western border would be affected by a unification of the two German states. The German Lower House of Parliament (8/11/1989 and 8/3/1990) and the People's Chamber of the GDR emphasised the irrevocability of the Polish western border.