A unified Germany once brought disaster to Europe, but why did the United States, the Soviet Union, Britain and France allow Germany to be unified?

Mainly because German reunification is the inevitable result. Since the Cold War, with the support of the United States, West Germany has quickly recovered from the ruins of World War II. By the 1960s, West Germany had become the second largest economy in the capitalist world after the United States. In contrast, the per capita income of East Germany is only one third of that of West Germany, and the per capita GDP is only half of that of West Germany. The disparity of economic gap has made many East Germans have the idea of emigration or smuggling. After the drastic changes in Eastern Europe, the ports around East Germany were opened, and a steady stream of East Germans entered West Germany through a third country.

Arguably, China is the last country that wants German reunification, but it has to bow to reality under pressure. First of all, France cannot restrict the development of Germany. Second, the relationship between France and Germany eased. In addition, during the Cold War, Europe's international discourse power was very small, so a unified Germany can enhance Europe's strength, and France can play a greater role in international affairs through Europe in the future.

For the United States, because the reunification of Germany was completed in the form of the merger of East Germany and West Germany, the main body of the Federal Republic of Germany has not changed, and the United States can move NATO's border eastward, closer to the core of the Soviet Union. In order to convince the United States, the leaders of West Germany also agreed that a unified Germany would stay within the framework of NATO and become a pillar of European security and defense. Due to the sharp decline in international status after World War II, Britain can only follow in the footsteps of the United States.

At that time, because of the serious domestic economic problems, the Soviet Union was in urgent need of western economic assistance to tide over the crisis. However, under the infiltration of the West, drastic changes began to take place abroad, and domestic waves surged. The Soviet Union was "willing but unable" to East Germany. Going out of East Germany in time can not only gain economic benefits, but also close the relationship with the West to a certain extent, which can kill two birds with one stone. In the end, West Germany persuaded the Soviet Union to provide economic assistance and loans to the Soviet Union, and paid the Soviet Union's withdrawal and resettlement expenses out of its own pocket.