Treaty of Non-Aggression Between Germany and The Soviet Union

The Treaty of Non-Aggression between Germany and the Soviet Union, also known as the Nazi–Soviet Pact and the Molotov–Ribbentrop Pact (after its chief architects, Soviet foreign minister Vyacheslav Molotov and German foreign minister Joachim von Ribbentrop) was a non-aggression pact, signed in Moscow in the late hours of 23 August 1939, at the height of the Nomonhan fighting in the far east between the Soviet Union and the Empire of Japan. The agreement gave Hitler the go ahead to invade Poland with impunity a week after the Soviets had gained the upper hand in the far east, and guaranteed Nazi Germany that they would not have to fight the USSR. In addition, the Pact assured a temporary non-involvement of the Soviet Union's participation in a European War, as well as separating both Germany and Japan from forming a military alliance, thus allowing Stalin to concentrate on Japan on the battles of Khalkhin Gol (Nomonhan). The Soviet Union would not invade Poland until the Nomonhan incident was officially concluded by the Molotov-Togo agreement, which it was on 15 September 1939, taking effect on 16 September, at which time Stalin ordered Soviet forces to invade Poland on 17 September 1939. Stalin's caution in complying with agreements had paid off; the USSR was the only primary combatant of WWII that did not fight a two-front war. It remained in effect until 22 June 1941, when Germany invaded the Soviet Union.

The pact has been seen by the political elites of the signatory countries as a way to revert and compensate the past territorial losses of both Germany and the Soviet Russia by the end of World War I: the Treaty of Brest-Litovsk (signed by Trotsky and the German Empire), which stripped a large part (from the Arctic to the Black Sea) of former western Russian Empire lands and the Treaty of Versailles, which stripped Germany from many of its territories and disrupted the territorial contiguity of the country by the creation of the Polish Corridor and the Free City of Danzig.

In addition to stipulations of non-aggression, the treaty included a secret protocol dividing Romania, Poland, Lithuania, Latvia, Estonia and Finland into German and Soviet spheres of influence, anticipating potential "territorial and political rearrangements" of these countries. Thereafter, Germany and the Soviet Union invaded, on September 1 and 17 respectively, their respective sides of Poland, dividing the country between them. Part of southeastern (Karelia) and Salla region Finland was annexed by the Soviet Union after the Winter War. This was followed by Soviet annexations of Estonia, Latvia, Lithuania, Bessarabia, Northern Bukovina and the Hertza region.

Of the territories of Poland annexed by the Soviet Union between 1939 and 1940, the region around Bialystok and a minor part of Galicia east of the San river around Przemysl were the only ones returned to the Polish state at the end of World War II.

Of all the territories annexed by the USSR due to the Molotov-Ribbentrop Pact, the ones detached from Finland (Petsamo, Karelia, Vyborg) and some smaller eastern parts of Estonia (Ivangorod, southern Lake Peipus area) and Latvia (Arbene) remained part of the Russian Federation, the successor state of the Soviet Union, after 1991.