Two Plus Four Agreement

The 1990 treaty between the two German states and the four Allied powers that settled the external aspects of German unity and restored Germany’s full sovereignty.

German reunification: The 1990 process that ended Germany’s division and established the Federal Republic of Germany across the former East and West. The treaty supplied the international settlement that made reunification possible.
Revolutions of 1989: The political upheavals that ended communist rule across much of Central and Eastern Europe in 1989. These upheavals created the conditions for German unity negotiations.
James Baker: The United States secretary of state from 1989 to 1992. Baker helped shape the American diplomatic approach to German unity and NATO membership.
German–Polish Border Treaty: The 1990 treaty in which unified Germany and Poland confirmed their existing border along the Oder and Neisse rivers. It gave separate bilateral force to the border commitment made in the settlement.
Oder–Neisse line: The border between Germany and Poland established along the Oder and Neisse rivers after the Second World War. Germany’s binding recognition of this border was a central treaty condition.
Peaceful Revolution: The largely nonviolent popular movement that brought down the East German communist government in 1989. Its pressure accelerated the collapse of East Germany’s political order.
Hans-Dietrich Genscher: The West German foreign minister from 1974 to 1992 and a leading advocate of détente and reunification. Genscher represented West Germany in the negotiations and pursued assurances for neighboring states.
Soviet Union: A socialist federal state that existed from 1922 until its dissolution in 1991. The Soviet Union accepted a unified Germany’s sovereignty and NATO membership.
NATO: A military alliance founded in 1949 by North American and European states for collective defense. The agreement allowed unified Germany to remain in NATO.
Fall of the Berlin Wall: The opening of Berlin’s border crossings on November 9, 1989, which ended the Wall’s role as a barrier. The opening made German reunification an immediate political question.

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