Geopolitical status in
in November 1939
Germany and annexed countries
Soviet Union and annexed countries
Neutral countries with Soviet military bases
Soviet–Finnish relations and politics
Until the beginning of the 19th century, Finland constituted the eastern part of the
Kingdom of Sweden. In 1809, to protect its imperial capital, Saint Petersburg, the
Russian Empire conquered Finland and converted it into an
 The resulting
Grand Duchy of Finland enjoyed wide autonomy within the Empire until the end of the 19th century, when Russia began attempts
to assimilate Finland as part of a general policy to strengthen the central government and unify the Empire through
russification. These attempts were aborted because of Russia's internal strife, but they ruined Russia's relations with the
Finns and increased support for Finnish self-determination movements.
The outbreak of
World War I in 1914 led to the collapse of the Russian Empire during the
Russian Revolution of 1917 and the
Russian Civil War of 1917–1920, giving Finland a window of opportunity; on 6 December 1917, the
Senate of Finland
declared the nation's independence. The new
Bolshevik Russian government was fragile, and civil war had broken out in Russia in November 1917; the Bolsheviks determined they could not hold onto peripheral parts of the old empire. Thus,
Soviet Russia (later the USSR) recognised the new Finnish government just three weeks after the declaration.
 Finland achieved full sovereignty in May 1918 after a 4-month
civil war, with the conservative
Whites winning over the socialist
Reds, and the expulsion of Bolshevik troops.
Finland joined the League of Nations in 1920, from which it sought security guarantees, but Finland's primary goal was cooperation with the
Scandinavian countries. The Finnish and Swedish militaries engaged in wide-ranging cooperation, but focused on the exchange of information and on defence planning for the
Åland Islands rather than on
military exercises or on stockpiling and deployment of
materiel. Nevertheless, the
government of Sweden carefully avoided committing itself to Finnish foreign policy.
 Finland's military policy included clandestine
defence cooperation with
The period after the Finnish Civil War till the early 1930s proved a politically unstable time in Finland due to the continued rivalry between the conservative and socialist parties of the war. The
Communist Party of Finland was declared illegal in 1931, and the nationalist
Lapua Movement organised
anti-communist violence, which culminated in a
failed coup attempt in 1932. The successor of the Lapua Movement, the
Patriotic People's Movement, only had a minor presence in national politics with at most 14 seats out of 200 in the
 By the late 1930s, the export-oriented Finnish economy was growing and the nation's extreme political movements had diminished.
A Soviet propaganda postcard from 1940 saying "the fascist dog growls" and referring to the Finnish
), the paramilitary forces that had a role in defeating the socialist
in Finland during the Civil War of 1918
After Soviet involvement in the Finnish Civil War in 1918, no formal peace treaty was signed. In 1918 and 1919, Finland conducted two unsuccessful military incursions across the Soviet border, the
Aunus expeditions, to annex
Karelian areas according to the
Greater Finland ideology of combining all
Finnic peoples into a single state. In 1920, Finnish communists based in the USSR attempted to assassinate the former Finnish
White Guard Commander-in-Chief, Marshal
Carl Gustaf Emil Mannerheim. On 14 October 1920, Finland and Soviet Russia signed the
Treaty of Tartu, confirming the new Finnish–Soviet border as the old border between the autonomous Grand Duchy of Finland and
Imperial Russia proper. Finland also received
Petsamo, with its
ice-free harbour on the
 Despite the signing of the treaty, relations between the two countries remained strained. The Finnish government allowed volunteers to cross the border to support the
East Karelian uprising in Russia in 1921, and Finnish communists in the Soviet Union continued to prepare for a
revanche and staged a cross-border raid into Finland, called the
Pork mutiny, in 1922.
 In 1932, the USSR and Finland signed a
non-aggression pact, which was reaffirmed for a ten-year period in 1934.
 While foreign trade in Finland was
booming, less than one percent of Finnish trade was with the Soviet Union.
 In 1934, the Soviet Union joined the League of Nations.
Joseph Stalin regarded it a disappointment that the Soviet Union could not halt the Finnish revolution.
 He thought that the pro-Finland movement in Karelia posed a direct threat to Leningrad and that the area and defences of Finland could be used to invade the Soviet Union or restrict fleet movements.
 During Stalin's rule, Soviet propaganda painted Finland's leadership as a "vicious and reactionary
fascist clique". Field Marshal Mannerheim and
Väinö Tanner, the leader of the
Finnish Social Democratic Party, were targeted for particular scorn.
 When Stalin gained absolute power through the Great Purge of 1938, the USSR changed its foreign policy toward Finland and began pursuing the reconquest of the provinces of Tsarist Russia lost during the chaos of the October Revolution and the Russian Civil War almost two decades earlier. The Soviet leadership believed that the old empire possessed the ideal amount of territorial security, and wanted the newly christened city of
Leningrad, only 32 km (20 mi) from the Finnish border, to enjoy a similar level of security against the rising power of
 In essence, the border between the Grand Duchy of Finland and Russia proper was never supposed to become international.
Rybachy Peninsula in 2008. The Soviet Union demanded that the peninsula, the northernmost point of Finland at the time, be ceded along with other areas to protect Soviet assets.
In April 1938,
Boris Yartsev contacted the Finnish Foreign Minister
Rudolf Holsti and Prime Minister
Aimo Cajander, stating that the Soviet Union did not trust Germany and that war was considered possible between the two countries. The Red Army would not wait passively behind the border but would rather "advance to meet the enemy". Finnish representatives assured Yartsev that Finland was committed to a policy of neutrality and that the country would resist any armed incursion. Yartsev suggested that Finland cede or lease some islands in the
Gulf of Finland along the seaward approaches to Leningrad; Finland refused.
Negotiations continued throughout 1938 without results. Finnish reception of Soviet entreaties was decidedly cool, as the violent collectivisation and purges in Stalin's Soviet Union resulted in a poor opinion of the country. Most of the Finnish communist elite in the Soviet Union had been executed during the Great Purge, further tarnishing the USSR's image in Finland. At the same time, Finland was attempting to negotiate a military cooperation plan with Sweden and hoping to jointly defend the
The Soviet Union and Nazi Germany signed the Molotov–Ribbentrop Pact in August 1939. The pact was nominally a
non-aggression treaty, but it included a secret protocol in which Eastern European countries were divided into
spheres of interest. Finland fell into the Soviet sphere. On 1 September 1939, Germany
began its invasion of Poland and two days later Great Britain and France declared war on Germany. On 17 September, the Soviet Union
invaded Eastern Poland. The
Baltic states were soon
forced to accept treaties allowing the USSR to establish military bases and to station troops on their soil.
 The government of Estonia accepted the
ultimatum, signing the agreement in September.
Lithuania followed in October. Unlike the Baltic states, Finland started a gradual
mobilisation under the guise of "additional
 The Soviets had already started intensive mobilisation near the Finnish border in 1938–39. Assault troops thought necessary for the invasion did not begin deployment until October 1939. Operational plans made in September called for the invasion to start in November.
Finnish soldiers gathering breakfast from a field kitchen during "additional
" at the Karelian Isthmus on 10 October 1939
On 5 October 1939, the Soviet Union invited a Finnish delegation to Moscow for negotiations.
J.K. Paasikivi, the Finnish envoy to Sweden, was sent to Moscow to represent the Finnish government.
 The Soviet delegation demanded that the border between the USSR and Finland on the
Karelian Isthmus be moved more westward to a point only 30 km (19 mi) east of
Finnish: Viipuri) and that Finland destroy all existing fortifications on the Karelian Isthmus. Likewise, the delegation demanded the cession of islands in the Gulf of Finland as well as
Rybachy Peninsula (
Finnish: Kalastajasaarento). The Finns would have to lease the
Hanko Peninsula for thirty years and permit the Soviets to establish a
military base there. In exchange, the Soviet Union would cede
Porajärvi municipalities from
Eastern Karelia, an area twice the size of the territory demanded from Finland.
 Accepting Soviet demands would have forced the Finns to dismantle their defences in
The Soviet offer divided the Finnish government, but was eventually rejected with respect to the opinion of the public and Parliament. On 31 October, Foreign Minister
Vyacheslav Molotov announced Soviet demands in public in the
Supreme Soviet. The Finns made two counteroffers whereby Finland would cede the
Terijoki area to the Soviet Union, which would double the distance between Leningrad and the Finnish border, far less than the Soviets had demanded,
 as well as the islands in the Gulf of Finland.
Shelling of Mainila and Soviet intentions
29 November 1939, foreign
at Mainila, where a
between Finland and the Soviet Union escalated into the Winter War
On 26 November 1939, an incident was reported near the Soviet village of
Mainila close to the border with Finland. A Soviet border guard post had been shelled by an unknown party resulting, according to Soviet reports, in the deaths of four and injuries of nine border guards. Research conducted by several Finnish and Russian historians later concluded that the shelling was a
false flag operation carried out from the Soviet side of the border by an NKVD unit with the purpose of providing the Soviet Union with a
casus belli and a pretext to withdraw from the non-aggression pact.
Molotov claimed that the incident was a Finnish artillery attack and demanded that Finland apologise for the incident and move its forces beyond a line 20–25 km (12–16 mi) away from the border.
 Finland denied responsibility for the attack, rejected the demands and called for a joint Finnish–Soviet commission to examine the incident. In turn, the Soviet Union claimed that the Finnish response was hostile, renounced the non-aggression pact and severed diplomatic relations with Finland on 28 November. In the following years,
Soviet historiography described the incident as Finnish provocation. Doubt on the official Soviet version was cast only in the late 1980s, during the policy of
glasnost. The issue continued to divide Russian historiography even after the
collapse of the Soviet Union in 1991.
In 2013, Russian President
Vladimir Putin stated at a meeting with military historians that the USSR launched the Winter War to "correct mistakes" made in determining the border with Finland after 1917.
 Opinion on the scale of the initial Soviet invasion decision is divided: some sources conclude that the Soviet Union had intended to conquer Finland in full, and cite the establishment of the puppet Finnish Communist government and the Molotov–Ribbentrop Pact's secret protocols as proof of their conclusions.
[F 10] Hungarian historian István Ravasz wrote that the
Central Committee had set out in 1939 that the former borders of the Tsar Empire were to be restored—including Finland.
 American political scientist
Dan Reiter stated that the USSR "sought to impose a regime change" and thus "achieve absolute victory". He quotes Molotov, who commented in November 1939 on the regime change plan to a Soviet ambassador that the new government "will not be Soviet, but one of a democratic republic. Nobody is going to set up Soviets over there, but we hope it will be a government we can come to terms with as to ensure the security of Leningrad."
Others argue against the idea of a complete Soviet conquest. American historian
William R. Trotter asserted that Stalin's objective was to secure Leningrad's flank from a possible German invasion through Finland. He stated that "the strongest argument" against a Soviet intention of full conquest is that it did not happen in either 1939 or during the Continuation War in 1944—even though Stalin "could have done so with comparative ease."
 Bradley Lightbody wrote that the "entire Soviet aim had been to make the Soviet border more secure."
 According to Russian historian A. Chubaryan in 2002, no documents had been found in Russian archives that support a Soviet plan to annex Finland. Rather, the objective was to gain Finnish territory and reinforce Soviet influence in the region.