[2] However, in reality the treaty opened the door for the first Soviet occupation of Lithuania and was described by The New York Times as "virtual sacrifice of independence.

[4] The Lithuanians refused to recognize Polish control and continued to claim legal and moral rights to the region throughout the interwar period.

[5] On August 23, 1939, the Soviet Union and Nazi Germany signed the Molotov–Ribbentrop Pact and divided Eastern Europe into spheres of influence.

[9] When on September 17 the Red Army invaded Poland, Soviet troops took over Vilnius Region, which according to the 1920 and 1926 Soviet–Lithuanian treaties was recognized to Lithuania.

[9] Lithuanian Minister of Foreign Affairs Juozas Urbšys arrived in Moscow on October 3 to meet with Soviet leaders.

During the meeting Joseph Stalin personally informed Urbšys about the Soviet–German secret protocols and showed maps of the spheres of influence.

[14] The Soviets argued that their army would protect Lithuania from possible attacks from Nazi Germany and that a similar treaty was already signed with Estonia.

[16] According to Lithuanian brigadier general Musteikis, who accompanied him, Urbšys said that Lithuania refused to annex the Vilnius Region as well as rejecting the Soviet garrisons.

German officials confirmed that the secret protocols were real, and informed Lithuanians that transfer of the territory in Suvalkija was not an urgent matter.

[14] Eventually, Nazi Germany sold this territory to the Soviet Union for 7.5 million dollars on January 10, 1941, in the German–Soviet Border and Commercial Agreement.

[19] Lithuanians in principle agreed to sign the mutual assistance treaty, but were instructed to resist Soviet bases as much as possible.

Alternatives included doubling the Lithuanian army, exchanging military missions, and building fortifications on the western border with Germany similar to the Maginot Line in France.

[16][20] On October 7, Lithuanian delegation, including General Stasys Raštikis and Deputy Prime Minister Kazys Bizauskas, returned to Moscow.

[16] Stalin refused the proposed alternatives, but agreed to reduce the number of Soviet troops to 20,000 – about the size of the entire Lithuanian army.

[9] Soviets wanted to sign the treaty right then to commemorate the 19th anniversary of Żeligowski's Mutiny and Lithuania's loss of Vilnius.

[14] Political rallies, organized in Vilnius demanding city's incorporation into the Byelorussian Soviet Socialist Republic, put additional pressure on Lithuanians and provided a sense of urgency.

In Lithuania, President Antanas Smetona doubted that it was worth gaining Vilnius for such a price and debated whether the negotiations could be broken off.

[24] The Lithuanians sought to limit Soviet bases to Vilnius Region and southern Lithuania, offering Pabradė, Nemenčinė, Naujoji Vilnia, and Alytus.

[25] The final location of the bases showed that the Soviets were more concerned with encircling Kaunas, the temporary capital, than with defending the country against a possible foreign attack.

[1] Russians emphasized that it was the second time the Soviet Union gave Vilnius to Lithuania[21] while the League of Nations failed to mediate the Polish–Lithuanian dispute.

[32] Poles resented the transfer and as soon as the Soviet Army left Vilnius, anti-Lithuanian riots broke out accusing Lithuanians of betrayal.

The Lithuanian Nationalists Union, ruling political party in Lithuania since the 1926 coup, used celebrations of return of the city to increase its prestige and popularity.

[30] While politicians publicly praised the Soviet Union and taunted "traditional Soviet–Lithuanian friendship," in private they understood this treaty was a serious threat to Lithuanian independence.

[33] On October 30 – November 1, when the bread price suddenly rose, clashes between local communists and Poles turned into a riot against the Jewish population.

[26] Lithuania had no counterweight to Soviet influence: its own forces were small, Germany was in effect Russia's ally, Poland was conquered, France and Great Britain had bigger issues in western Europe.

[11] After months of intense propaganda and diplomatic pressure, the Soviets issued an ultimatum on June 14, 1940 – the same day when the world's attention was focused on the fall of Paris during the Battle of France.