The Treaty on the Final Settlement With Respect to Germany (German: Vertrag über die abschließende Regelung in Bezug auf Deutschland), or the Two Plus Four Agreement (German: Zwei-plus-Vier-Vertrag; short: German Treaty), was negotiated in 1990 between the Federal Republic of Germany and the German Democratic Republic (the eponymous "Two"), and the Four Powers which occupied Germany at the end of World War II in Europe: France, the Soviet Union, the United Kingdom, and the United States. In the treaty the Four Powers renounced all rights they held in Germany, allowing a united Germany to become fully sovereign the following year.
On 2 August 1945, the Potsdam Agreement, promulgated at the end of the Potsdam Conference, among other things agreed on the initial terms under which the Allies of World War II would govern Germany. A provisional German–Polish border known as the Oder–Neisse line awarded, in theory within the context of that "provisional border", most of Germany's eastern provinces to Poland and the Soviet Union. Those agreements reached were provisional and the agreement stipulated that the situation would be finalised by "a peace settlement for Germany to be accepted by the Government of Germany when a government adequate for the purpose is established" (Potsdam Agreement 1.3.1). Parts of those above mentioned agreements were burdened with controversy from several sources e.g., Churchill's comment about stuffing the Polish goose too full (of German lands). The overall "German Question" became one of the salient and crucial issues of the long-running Cold War, and until it ended in the late 1980s, little progress had been made in the establishment of a single government of Germany adequate for the purpose of agreeing to a final settlement. This meant that in some respects (largely, but not only, technical), Germany did not have full national sovereignty.
Several developments in 1989 and 1990, collectively termed Die Wende and the Peaceful Revolution, led to the fall of the Berlin Wall and the collapse of the SED in the German Democratic Republic (GDR or East Germany). In the March 18, 1990 national election in the GDR an electoral alliance of parties that favored German reunification via article 23 of the Basic Law for the Federal Republic of Germany won a plurality. To achieve unity and full sovereignty, both German states were willing to accept the terms of the Potsdam Agreement that affected Germany. It was then possible for all international parties to negotiate a final settlement.
The Treaty on the Final Settlement with Respect to Germany was signed in Moscow, Russia (known at the time as the Soviet Union), on 12 September 1990, and paved the way for German reunification on 3 October 1990. Under the terms of the treaty, the Four Powers renounced all rights they formerly held in Germany, including those regarding the city of Berlin. Upon deposit of the last instrument of ratification, united Germany became fully sovereign on 15 March 1991.
The treaty allows Germany to make and belong to alliances, without any foreign influence in its politics. All Soviet forces were to leave Germany by the end of 1994. Before the Soviets withdrew, Germany would only deploy territorial defense units not integrated into the alliance structures. German forces in the rest of Germany were assigned to areas where Soviet troops were stationed. After the Soviets withdrew, the Germans could freely deploy troops in those areas, with the exception of nuclear weapons. For the duration of the Soviet presence, Allied troops would remain stationed in Berlin upon Germany's request.
Germany undertook to reduce its armed forces to no more than 370,000 personnel, no more than 345,000 of whom were to be in the Army and the Air Force. These limits would commence at the time that the Treaty on Conventional Armed Forces in Europe would enter into force, and the treaty also took note that it was expected that the other participants in the negotiations would "render their contribution to enhancing security and stability in Europe, including measures to limit personnel strengths." Germany also reaffirmed its renunciation of the manufacture, possession of, and control over nuclear, biological, and chemical weapons, and in particular, that the Nuclear Non-Proliferation Treaty would continue to apply in full to the unified Germany (the Federal Republic of Germany). No foreign armed forces, nuclear weapons, or the carriers for nuclear weapons would be stationed or deployed in six states (the area of Berlin and the former East Germany), making them a permanent Nuclear-Weapon-Free Zone. The German Army could deploy conventional weapons systems with nonconventional capabilities, provided that they were equipped and designed for a purely conventional role. Germany also agreed to use military force only in accordance with the United Nations Charter.
Another of the treaty's important provisions was Germany's confirmation of the by now internationally recognised border with Poland, and other territorial changes in Germany that had taken place since 1945, preventing any future claims to lost territory east of the Oder-Neisse line (see also Former eastern territories of Germany) which had historically been part of Germany for centuries before 31 December 1937. The treaty defined the territory of a 'united Germany' as being the territory of East Germany, West Germany and Berlin, prohibiting Germany from making any future territorial claims. Germany also agreed to sign a separate treaty with Poland reaffirming the present common border, binding under international law, effectively relinquishing these territories to Poland. This was done on 14 November 1990 with the signing of the German-Polish Border Treaty. Furthermore, the Berlin Republic was required by the treaty to amend its Basic Law so as to be constitutionally prohibited from accepting any application for incorporation into Germany from territories outside the territories of East Germany, West Germany and Berlin.
Although the treaty was signed by the western and eastern German states as separate entities, it was also ratified by united Germany (the Federal Republic of Germany) in accordance with the treaty.
After the Soviet Union dissolved itself in December 1991, the command unit of the Soviet Group of Soviet Forces in Germany devolved to the Russian Federation. The German government subsequently recognized the Russian Federation's claim to be the successor state of the Soviet Union, including the right to maintain troops in Germany until the end of 1994. However, with post-Soviet Russia facing severe economic hardship, President Boris Yeltsin ordered Russian troop deployment in Germany to be reduced to levels significantly below those permitted in the Treaty. The last Russian troops left Germany at the end of August in 1994, four months before the treaty deadline.
In the first decade of the 21st century, the Bundeswehr underwent a gradual transformation to a fully professional force. By 2011, the year Germany voluntarily suspended conscription, the Bundeswehr had retained fewer than 250,000 active duty personnel – barely two thirds of the country's treaty limit of 370,000.
The treaty has been alleged to have been violated on a number of occasions. In 2006, German News Information Services argued that "an international lawsuit should be initiated against the development of installations at Leipzig Airport in preparation for service in NATO and EU combat missions". Similarly, manoeuvres including NATO-troops in Trollenhagen, Mecklenburg-Vorpommern in the area of the former East Germany have also been questioned. Under one interpretation of the treaty, only German forces may be deployed in the area of the former East Germany. Many countries believe that Germany's hosting of American nuclear weapons as part of NATO's nuclear weapons sharing program are a violation. Although the weapons are under American control, they can be used by the Bundeswehr during a time of war under agreement, and German pilots and staff practice handling them. It has been argued that this violates Germany's treaty commitments renouncing control over nuclear weapons, as well as the NPT, which the treaty committed Germany to. In September 2007, France offered Germany joint control over its nuclear arsenal, but the Germans rejected this.
Historian Stephen F. Cohen asserted in 2005 that a commitment was given that NATO would never expand further east, but according to Robert Zoellick, then a US State Department official involved in the Two Plus Four negotiating process, this appears to be a misperception; no formal commitment of the sort was made. On 7 May 2008 the former Soviet leader Mikhail Gorbachev, in an interview with the British newspaper The Daily Telegraph, stated his view that such a commitment had been made:
"The Americans promised that NATO wouldn't move beyond the boundaries of Germany after the Cold War but now half of central and eastern Europe are members, so what happened to their promises? It shows they cannot be trusted."
However, in a 2014 interview he stated that the topic of "NATO expansion" was "not discussed at all", nevertheless maintaining that the decision to expand NATO into the east was a "violation of the spirit of the statements and assurances made to us in 1990."
In reality, such a commitment was never made; the issue of expanding NATO into Central and Eastern European states wasn't even on the agenda at that time, since all of them were Warsaw Pact members and most still had substantial Soviet combat units stationed on their soil.
The two-plus-four-treaty had the function of a peace treaty, but it was not called a peace treaty. This could not be in their interest "for financial reasons," said the German State Secretary Friedrich Voss at that time. The reason was the open question of German reparations for World War II, especially in the case of Greece. Today Berlin argues that the Greeks should have made their demands in 1990.