The Treaty of Berlin is signed. Germany and the Soviet Union each pledge neutrality in the event of an attack on the other by a third party for the next five years.

The Treaty of Berlin was a treaty signed on 24 April 1926 under which Germany and the Soviet Union pledged neutrality in the event of an attack on the other by a third party for five years. The treaty reaffirmed the German–Soviet Treaty of Rapallo (1922).

The Union of Soviet Socialist Republics (USSR), commonly known as the Soviet Union, was a transcontinental country that spanned much of Eurasia from 1922 until it dissolved in 1991. During its existence, it was the largest country by area, extending across eleven time zones and sharing borders with twelve countries, and the third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of national republics, the largest and most populous of which was the Russian SFSR. In practice, its government and economy were highly centralized. As a one-party state governed by the Communist Party of the Soviet Union (CPSU), it was the flagship communist state. Its capital and largest city was Moscow.