Having signed mutual aid treaties with the Baltic states, the USSR turned to Finland with a proposal to conclude a similar agreement. Finland refused. The Minister of Foreign Affairs of this country, E. Erkko, stated that "Finland will never take a decision similar to those made by the Baltic states. If this happens, it will be only in the worst case." The origins of the Soviet-Finnish confrontation are largely explained by the extremely hostile, aggressive stance of the ruling circles of Finland towards the USSR. Former Finnish President P. Svinhuvud, in which Soviet Russia voluntarily recognized the independence of its northern neighbor, said that "any enemy of Russia must always be a friend of Finland." In the mid 30s. M. Litvinov, in an interview with the Finnish envoy, stated that "in no neighboring country is there such open propaganda for attacking the USSR and tearing off its territory, as in Finland."

After the Munich agreement of Western countries, the Soviet leadership began to show particular insistence on Finland. B. The course of 1938-1939. negotiations were conducted during which Moscow sought to ensure the safety of Leningrad by moving the border on the Karelian Isthmus. Instead, Finland was offered the territory of Karelia, and much larger in size than the land that was supposed to be transferred to the USSR. In addition, the Soviet government promised to allocate a certain amount for the resettlement of residents. However, the Finnish side stated that the territory ceded to the USSR is insufficient compensation. On the Karelian Isthmus there was a well developed infrastructure: a network of railways and highways, buildings, warehouses and other facilities. The territory, transferred by the Soviet Union to Finland, was an area covered with forests and swamps. In order to turn this territory into a habitable and economical area, it was necessary to invest a lot of money.

Moscow did not give up hope for a peaceful resolution of the conflict and offered various options for concluding a treaty. At the same time, Stalin firmly stated: "Since we cannot move Leningrad, we will move the border in order to secure it." At the same time, he referred to Rib-bentrop, who explained the German attack on Poland by the need to secure Berlin. Large-scale military construction unfolded on both sides of the border. The Soviet Union was preparing for offensive operations, and Finland - for defensive. Finnish Foreign Minister Erkko, expressing the mood of the government, confirmed: "Everything has its borders. Finland cannot accept the proposal of the Soviet Union and will defend its territory, its inviolability and independence by any means."

The Soviet Union and Finland did not take the path of finding an acceptable compromise. Stalin's imperial ambitions made themselves felt this time too. In the second half of November 1939, diplomatic methods gave way to threats and saber-rattling. The Red Army hastily prepared for hostilities.

On November 27, 1939, V.M. Molotov made a statement in which he reported that “yesterday, November 26, the Finnish Whiteguard launched a new vile provocation, firing a Red Army unit in artillery fire, located in the village of Mineil on the Karelian Pere- the neck. " Disputes over the question of whose side these shots were fired are still ongoing. Already in 1939, the Finns tried to prove that the shelling could not have been carried out from their territory, and the whole story with the “Maynil incident” was nothing but a provocation of Moscow.

On November 29, taking advantage of the shelling of its border positions, the USSR terminated the non-aggression pact with Finland. November 30 began hostilities. On December 1, on the Finnish territory, in the city of Terioki (Zelenogorsk), where the Soviet troops entered, on the initiative of Moscow there was an educational, but new, "people's government" of Finland led by the Finnish communist O. Kuusinen. The next day, between the USSR and the government of Kuusinen, called the government of the Finnish Democratic Republic, an agreement of mutual assistance and friendship was concluded.

Events, however, did not develop as well as hoped in the Kremlin. The first stage of the war (November 30, 1939 - February 10, 1940) was especially unsuccessful for the Red Army. This was largely due to the underestimation of the fighting efficiency of the Finnish troops. Break through the line of Mannerheim - a complex of fortifications built in 1927-1939. and stretched along the front for 135 km, and to a depth of 95 km, it was not possible. During the battles the Red Army suffered huge losses.

In December 1939, the command stopped unsuccessful attempts to advance deep into Finnish territory. Began a thorough preparation of a breakthrough. The North-Western Front was formed, headed by S. K. Timoshenko and a member of the Military Council A. A. Zhdanov. The front consisted of two armies, which were led by KA Meretskov and VD Grendal (replaced at the beginning of March 1940 by F. A. Parusinov). The total number of Soviet troops was increased 1.4 times and brought up to 760 thousand people.

Strengthened its army and Finland, receiving from abroad military equipment and equipment. From Scandinavia, the USA and other countries, 11.5 thousand volunteers arrived to fight the Soviets. England and France developed their plans of military action, intending to enter the war on the side of Finland. In London and Paris, they did not hide their hostile plans towards the USSR.

February 11, 1940 began the final stage of the war. Soviet troops went on the offensive and broke through the Mannerheim Line. The main forces of the Karelian army of Finland were defeated. On March 12 in the Kremlin, after short negotiations, a peace treaty was concluded. Military operations on all fronts stopped at 12 o'clock on March 13. In accordance with the signed agreement, the Karelian Isthmus, the western and northern shores of Lake Ladoga, a number of islands in the Gulf of Finland were included in the USSR. The Soviet Union was leased for 30 years to the Hanko Peninsula to build a naval base on it, "capable of defending the entrance to the Gulf of Finland from aggression."

The price of victory in the "winter war" was extremely high. In addition to the fact that the Soviet Union as an “aggressor state” was expelled from the League of Nations, during the 105 days of war the Red Army lost at least 127 thousand people killed, dead from wounds and missing. About 250 thousand military servants were wounded, frostbite, contused.

The Winter War demonstrated major miscalculations in the organization and training of the Red Army troops. Hitler, who closely followed the course of events in Finland, formulated the conclusion that the Red Army was a "colossus on clay feet" that the Wehrmacht could easily cope with. Certain conclusions from the military campaign of 1939-1940. done in the Kremlin. Thus, K. Ye. Voroshilova, as Commissar of Defense, replaced S. M. Timoshenko. The implementation of a set of measures aimed at strengthening the defense capability of the USSR began.

However, during the “winter war” and after its end, no substantial security was achieved in the north-west. Although the border was removed from Leningrad and the Murmansk Railway, this did not prevent the fact that during World War II Leningrad fell into the blockade ring. In addition, Finland did not become friendly, or at least neutral, to the USSR — a revanchist element that relied on the support of Nazi Germany prevailed in its leadership.