The pact delineated the spheres of interest between the two powers, confirmed by the supplementary protocol of the German–Soviet Frontier Treaty amended after the joint invasion of Poland. It remained in force for nearly two years, until the German government of Adolf Hitler ended the pact by launching an attack on the Soviet positions in Eastern Poland during Operation Barbarossa on 22 June 1941.
The clauses of the Nazi-Soviet Pact provided a written guarantee of non-belligerence by each party towards the other, and a declared commitment that neither government would ally itself to, or aid, an enemy of the other party. In addition to stipulations of non-aggression, the treaty included a secret protocol that divided territories of Poland, Lithuania, Latvia, Estonia, Finland, and Romania into German and Soviet "spheres of influence", anticipating "territorial and political rearrangements" of these countries. Thereafter, Germany invaded Poland on 1 September 1939. Soviet Union leader Joseph Stalin ordered the Soviet invasion of Poland on 17 September, one day after a Soviet-Japanese ceasefire at the Khalkhin Gol came into effect. In March 1940, parts of the Karelia and Salla regions in Finland were annexed by the Soviet Union after the Winter War. This was followed by Soviet annexations of Estonia, Latvia, Lithuania, and parts of Romania (Bessarabia, Northern Bukovina, and the Hertza region). Advertised concern about ethnic Ukrainians and Belarusians had been proffered as justification for the Soviet invasion of Poland. Stalin's invasion of Bukovina in 1940 violated the pact, as it went beyond the Soviet sphere of influence agreed with the Axis.
The territories of Poland annexed by the Soviet Union after the 1939 Nazi-Soviet invasion of Poland remained in the USSR at the end of World War II. The new border was set up along the Curzon Line. Only the region around Białystok and a small part of Galicia east of the San river around Przemyśl were returned to the Polish state from that line. Of all other territories annexed by the USSR in 1939–40, the ones detached from Finland (Karelia, Petsamo), Estonia (Ingrian area and Petseri County) and Latvia (Abrene) remain part of the Russian Federation, the successor state of the USSR upon the dissolution of the Soviet Union in 1991. Northern Bukovina, Southern Bessarabia and Hertza remain part of Ukraine. After the war, von Ribbentrop was convicted of war crimes and executed. Molotov died aged 96 in 1986, five years before the USSR's dissolution.
The existence of the secret protocol was denied by the Soviet government until 1989, when it was finally acknowledged and denounced. Some time later, the new Russian nationalists and revisionists including Russian amateur negationist Alexander Dyukov and Nataliya Narotchnitskaya, whose book carried an approving foreword by the Russian foreign Minister Sergei Lavrov, described the pact as a necessary measure because of the British and French failure to enter into an anti-fascist pact. Vladimir Putin has also defended the pact.
The outcome of World War I was disastrous for both the German Reich and the Russian Soviet Federative Socialist Republic. During the war, the Bolsheviks struggled for survival, and Vladimir Lenin recognised the independence of Finland, Estonia, Latvia, Lithuania and Poland. Moreover, facing a German military advance, Lenin and Trotsky were forced to enter into the Treaty of Brest-Litovsk, which ceded massive western Russian territories to the German Empire. After Germany's collapse, a multinational Allied-led army intervened in the Russian Civil War (1917–22).
On 16 April 1922, Germany and the Soviet Union entered the Treaty of Rapallo, pursuant to which they renounced territorial and financial claims against each other. Each party further pledged neutrality in the event of an attack against the other with the 1926 Treaty of Berlin. While trade between the two countries fell sharply after World War I, trade agreements signed in the mid-1920s helped to increase trade to 433 million Reichsmarks per year by 1927.
At the beginning of the 1930s, the Nazi Party's rise to power increased tensions between Germany and the Soviet Union along with other countries with ethnic Slavs, who were considered "Untermenschen" (inferior) according to Nazi racial ideology. Moreover, the anti-Semitic Nazis associated ethnic Jews with both communism and financial capitalism, both of which they opposed. Nazi theory held that Slavs in the Soviet Union were being ruled by "Jewish Bolshevik" masters. In 1934, Hitler himself had spoken of an inescapable battle against both Pan-Slavism and Neo-Slavism, the victory in which would lead to "permanent mastery of the world", though he stated that they would "walk part of the road with the Russians, if that will help us." The resulting manifestation of German anti-Bolshevism and an increase in Soviet foreign debts caused German–Soviet trade to dramatically decline. Imports of Soviet goods to Germany fell to 223 million Reichsmarks in 1934 as the more isolationist Stalinist regime asserted power and the abandonment of post–World War I Treaty of Versailles military controls decreased Germany's reliance on Soviet imports.