The unification of Germany, the external aspects of which were codified in the "two-plus-four" agreement signed by the four original occupying powers in September 1990, ends an important period in East-West relations — and in Soviet diplomacy. For the Soviet Union, the German Question — how to treat Germany — was the problem of European politics during the postwar period. The basic Soviet objective after 1945 remained constant: to prevent the resurgence of a powerful Germany and to maintain as much control over developments in Germany as possible.