The Soviet-Japanese non-aggression treaty was signed in Moscow on 13 April 1941.

The whole system of the Soviet diplomatic initiatives in the international relations was focused on preserving peace at any cost, keeping at bay those forces, which were seeking military solutions to their political aspirations, and winning time to consolidate the defence of the Soviet Union.

As the Soviet political and military leadership issued from the ideological premises, they foresaw that the most probable enemy of the socialist Soviet Union would be nazi Germany. However, they were afraid of the possibility to face an international crusade mounted by the Western democracies together with Germany. To the Kremlin such a perspective looked very probable in view of the collapse of the Anglo-Franco-Soviet talks in the spring and summer of 1939, as well as mounting anti-Soviet propaganda in the West. In such circumstances the Soviet Union accepted the German proposal to conclude the non-aggression treaty, which was signed on 23 August 1939.

The conclusion of the non-aggression treaty hardly changed anything in the nazi Germany's stance against communism; it did not weaken the Kremlin's suspicions about the aggressive plans of the III Reich against the Soviet Union either. But it lent Moscow some time before the ultimate confrontation, and what is more - possibility to undertake some strategic political and economical steps, crucial for the defensive capabilities of the Soviet state.

First of all, in the conditions of the collapse of the Polish state in September 1939, could introduce, without conflicting with Germany, eight armies under the command of Marshal Semyon Timoshenko and General Mikhail Kovalev to the Western Ukraine and Byelorussia. That move deprived Germany of a convenient operational basis for further aggression against the Soviet Union. The soviet border was moved westward some 250 to 300 km, and put under the Soviet control the system of the Polish frontier fortifications (so-called Railway Line), designed to protect operational deployment of invading forces.

The German command became very much disappointed with such a turn of the operational situation, whereas Sir Winston Spencer Churchill, at that time the First Lord of the Admiralty, deemed it the first step towards mounting an anti-fascist coalition:

Russia has pursued a cold policy of self-interest. (...) I would have preferred that the Russians should be standing on their present line as the friends and allies of Poland instead of invaders. But that the Russian armies should stand on this line was clearly necessary for the safety of Russia against the Nazi menace. (...) I cannot forecast to you the action of Russia. It is a riddle wrapped in a mystery inside an enigma; but perhaps there is a key. That key is Russian national interest. It cannot be in accordance with the interest or safety of Russia that Germany should plant itself upon the shores of the Black Sea, or that it should overrun the Baltic States and subjugate the Slavonic peoples of southeastern Europe. [Churchill W. S. L. (1986a).]

Another problem was brewing on the north-western border of the Soviet Union. Close alliance between Germany and Finland, which resulted in rapid growth of the Finnish military power between the summer and autumn 1939, as well as intensive works to expand Finnish fortifications (so-called Mannerheim Line) just 32km from Leningrad (Petersburg) induced the Soviet leadership to initiate in October and November negotiations with the Finnish government regarding exchange of frontier lands, which could bring a substantial rectification of the Soviet-Finnish border, and improve the defence of the north-western sector.

The Finnish government broke the negotiations under the pressure of England, France and the United States, which offered military support to Finland in case of an armed conflict with the USSR. Whereas the German diplomacy, through the fascist organizations in Finland, promised to support Finnish territorial claims. The crisis in the Soviet-Finnish relations eventually brought an armed conflict, which ended on 12 March 1940. The peace agreement between the two countries, extended on 11 October with additional protocols, improved the strategic situation on the north-western border, and what is more, obliged both sides to renounce any aggression.

A very important problem of the Soviet foreign policy was to neutralize fascist influence in the Baltic countries. Since the defeat of Poland, German influence in Lithuania, Lettonia and Estonia was mounting month by month. Turning them into satellites of the III Reich would create another strategic problem to the Soviet Union. That is why already in the autumn of 1939 USSR proposed Estonia, Lettonia and Lithuania conclusion of mutual assistance agreements. Despite of numerous problems, such agreements were signed in September and October. Those agreements provided for deployment of the Soviet military, air and naval bases in selected areas of the region. However, activation of the radical fascist groupings, frequent provocations against the Soviet servicemen, as well as attempts of the respective governments to come to terms with Germany behind the back of Moscow, since the spring 1940 fostered activation of the radical leftist groupings, including underground communist movement. In result of that radicalization fascist régimes of Estonia, Lettonia and Lithuania were overthrown, and replaced by popular governments (June-July 1940).

The revolutionary process in Baltic countries logically led to their reunion with the USSR. In July and August 1940 new legislations of Estonia, Lettonia and Lithuania passed laws declaring them Soviet republics, and addressed Moscow with petitions to admit them into the Union of Soviet Socialist Republic. Those events had tremendously improved the strategic situation on the west: The state border had been substantially shortened, USSR had acquired a broad access to the Baltic Sea, and eliminated possibility of a sneak German attack right into vital areas of the Soviet Union from the Baltic bridgehead.

Soviet diplomats paid close attention to the Balkan region as well, where the German diplomacy and business was making bold steps. German political and military penetration of the Balkans pursued tho goals critical to the invasion of the Soviet Union. First, Germany would gain a convenient oil and food supply base in the rears of the East front, and second, it would create convenient initial positions for attacking south-western regions of the USSR. Therefore, stalling the German expansion in the Balkans became one of the main tasks of the Soviet diplomacy.

First of all there was the unresolved problem of Bessarabia, since 1918 occupied by Romania. The Soviet Union also wanted to acquire northern Bukovina; formally because its ethnic composition made it close to the Ukraine, but actually because across Bukovina ran strategic roads and railways linking Bessarabia with Western Ukraine. On 26 June 1940 the Soviet diplomacy sent to the Romanian government a note demanding return of the occupied territories as the guarantee of the lasting peace. Bucharest, left without a real diplomatic support, agreed, and on 28-30 June the Red Army recovered the occupied territories and established the state border along the rivers Prut and Danube. The new borderline was moved some 200 km westward from the old one, but at the same time Berlin rendered political guarantees to the régime of Marshal Ion Antonescu, and started building up its economical and military presence in Romania.

German penetration of Romania, Bulgaria, Yugoslavia and Turkey alarmed the Soviet Union very seriously. In order to dismiss Soviet suspicions about the German intentions, the German foreign minister Joachim Ribbentrop in the letter to the Soviet leader Joseph Stalin from 13 November 1940 proposed a meeting with the Soviet foreign minister Vyacheslav Molotov to discuss disputable issues. Such a meeting indeed took place in Berlin, but it only augmented Molotov's and other Soviet leaders' conviction that the war with Germany was inevitable. Therefore, in the spring of 1941 there was signed the treaty of friendship and non-aggression with Yugoslavia, which was thought as a camouflaged message of the Soviet Union's readiness to collaborate with any country menaced by the fascist aggression.

Simultaneously with the Balkan affairs, the Soviet diplomacy worked on securing neutrality of Norway, Sweden and Turkey in case of a German aggression. Since the end of 1940 improved relations with Great Britain, and, especially on the ground of mutual trade, with the United States. Finally, on 13 April 1941 the non-aggression treaty with Japan was signed.

Overall, the number of political initiatives the Soviet diplomacy undertook in 1939-1941, despite of ideological differences between the communist USSR and democratic or fascist states, definitely improved the strategic position of the Soviet state, and in further perspective built the conditions for the collapse of the German concept of the lightning war and created the basis for the future anti-fascist coalition. The coalition that eventually dealt the ultimate defeat to the fascist "new world order".