The German-Soviet Treaty of Friendship and Border between the USSR and Germany was signed 80...

On September 28, 1939, the German-Soviet Frontier Treaty was signed by Joachim von Ribbentrop and Vyacheslav Molotov. It redrew German and Soviet spheres of influence in central Europe and transferred most of Lithuania to the USSR. From the article:

"The German-Soviet Treaty of Friendship and Border between the USSR and Germany was signed 80 years ago
28 September 1939
70 years ago, on September 28, 1939 as a result of negotiations between V.M. Molotov, Peoples’ Commissar of foreign affairs of USSR and I. fon Ribbentrop, the Minister of foreign affairs of Germany, there was signed the agreement on friendship and border between USSR and Germany. Up to the present this agreement continues to provoke political battles. It was a final point in a diplomatic struggle that had been taking place on the eve of the Second World War.

Due to the increasing political tension in the world during 1939, the Soviet Union had tried to conclude an agreement with Great Britain, France and other European countries on the mutual repulse in case of aggression from Germany. However the evasive attitude of Western democratic leaders who wanted to cause a clash between USSR and Germany for their proper profit, had forced the Soviet leaders to seek other ways to delay the war. On August 23, 1939 the USSR and Germany signed the famous non-aggression pact of Molotov-Ribbentrop that guaranteed that the parties would not attack each other in case one of them got involved in war.

The pact and secret protocols signed along with it freed the hands of Germany and on September 1, 1939 it invaded Poland without obstruction occupying its Western parts in a brief space of time. On September 17 the Soviet armies occupied the territories of Western Ukraine and Western Belorussia that made a part of Poland. That was the division of spheres of influence between Germany and USSR stipulated by secret protocols. The agreement of September 28, 1939 and its secret protocols had fixed the fact of Poland’s division and set the Western border of the USSR.

On December 24, 1989 the Convention of Peoples’ Deputies assessed from political and juridical points of view the agreements of August 23 and September 28, 1939. The convention has acknowledged that the agreements had been concluded in a critical political situation and were meant to ward off the USSR the upcoming war. However the secret protocols had been signed with violation of legal regulations as they allowed the encroachment on sovereignty and independence of third countries. Therefore the convention has declared them legally unsound and invalid from the moment they were signed.

Most of contemporary scientists and politicians also assess with criticism the agreement on peace and borders of September 28 considering it as mistake of the Soviet leaders. The consequences of this mistake up to the present leave negative traces on the external politics of our country."