At first, Soviet foreign policy in the interwar period had high expectations. The Bolsheviks, in their first years, acted deliberately provocatively. They exposed all Tsarist secret treaties, cut all legal ties with all other nations made by the Tsarist regime, and issued the Decree of Peace. Expecting their communist revolution to spread, they adopted a unique approach to the Brest-Litovsk negotiations. The troops of the Central Powers were bombarded with propaganda while the Soviet delegates wasted as much time as possible. Von Kuhlmann, the German foreign secretary remarked that "The Moscovites had a woman as a delegate—of course simply for propaganda reasons."

German and Soviet demands were almost irreconcilable at the treaty, and eventually, after around two months of negotiation, the Germans lost patience, recognised the government of the Ukraine, and began to negotiate with them instead. Frustrated with continued German demands for cessions of territory, Trotsky on February 10 announced a new policy. Russia unilaterally declared an end of hostilities against the Central Powers, and Russia withdrew from peace negotiations with the Central Powers - a position summed up as "no war — no peace". Other Bolshevik leaders denounced Trotsky for exceeding his instructions and exposing Soviet Russia to the threat of invasion. Trotsky subsequently defended his action on the grounds that the Bolshevik leaders had originally entered the peace talks in the hope of exposing their enemies' territorial ambitions and rousing the workers of central Europe to revolution in defense of Russia's new workers' state.

The Soviet foreign ministry, or Narkomindel, began to realise that as the Russian civil war drew to a close, that Russia's position was not as strong as it had been. Worker movements in Hungary and Germany had been crushed, and the country itself was ravaged by war and surrounded by hostile states. It was not a member of the League of Nations, and began trying to make as many economic and political connections as possible. This lead to a rapprochement with Germany - both countries could be seen as the outsider states, with neither in the League of Nations, and both had dim regard in the foreign policies of the Western powers.

This lead to the Treaty of Rapallo in 1922, which was a spinoff of the Genoa Conference, which included Germany and the Soviet Union. It had broken down when France demanded that the Soviets assume the prewar debt incurred by the tsarist regime and on immediate reparations by the Germans to the USSR. The German and Russian delegates quietly slipped away and met at Rapallo. What was agreed was fairly straightforward. This is the long version but basically it undid much of the Brest-Litovsk treaty and agreed that both sides waive their claim to reparations (some of the treaty is not covered here, as there was a supplementary agreement regarding some of the Russian border states).

The Soviet foreign policies of the 1920s were constantly undermined by the "twin track" approach which they often adopted. This was to undergo regular diplomatic approaches with countries, while at the same time attempting to forment revolution in those countries. There were some fears over German rapprochement with the Allies, but the re-affirmation of the Treaty of Rapallo at the Treaty of Berlin in 1926 and economic and military connections between the two countries continued to expand. To give an example, there was an agreement where Russian civil servants were sent to Berlin to learn skills. There were more, but this is already quite long, so I'll press on.

The Soviets began to become recognised by many of the European powers, but Soviet press continued to give the impression that capitalism was on the verge of attacking the Soviet state once again (the first time being during the civil war). This created a somewhat paranoid Soviet approach to world politics, and while this may have been intended to motivate the workers in Stalin's ongoing industrialisation process, it lead to many countries regarding the USSR with suspicion. There were also setbacks in the Far East, with the massacre of communists by the Nationalist party of Chiang Kai-Shek in Shanghai in 1927 damaging the Comintern idea of a "united front from above", which encouraged foreign communists to work with other groups on the left of the political sphere.

As the 1920s came to end however, European groups began to see the USSR as a kind of moral leader, thanks to Litvinov's demand for immediate and total disarmament at the Geneva Preparatory Commission on Disarmament (1927) and successful propaganda. This was furthered by the signing of neutrality and non-aggression pacts with many of her neighbours, including symbolic ones with Poland and France (1932). It also benefitted ideologically from the crash of 1929, as this was an obvious failure of the capitalist system from which the USSR remained aloof. However, this was to have impact on the USSR in the 1930s.

The Japanese invasion of Manchuria had implications for Siberia and the lack of a firm response to the crisis by the Western powers likely made Stalin suspicious of the West's intentions. A conspiracy of imperialist powers is often seen as more plausible to Stalin as an explanation of Western actions than mere weakness or incompetence. Stalin soon pragmatically resumed relations and arms deliveries to Chiang Kai Shek, and military strength in the Soviet Far East was steadily increased. The situation was also changing in Europe. The Soviet interpretation of events in Germany was that the polarisation in politics could only ultimately lead to a strengthening of the KPD and that the Nazis "short-lived' success would presage some sort of left-wing revolution. As a result the KPD was ordered to attack the middle ground of German politics, labelling the SPD 'social fascists'. Stalin was not the only one to underestimate the power of Hitler and the Nazis. After a year of confused signals from Berlin, it became quite obvious in the Kremlin that the German link was no longer to be relied upon.

Although economic relations continued (between Russia and Germany), the secret military cooperation was ended by Hitler, the KPD was destroyed, the tone of the Nazi press was distinctly anti-Soviet and the expansionist aims of Hitler's foreign policy were openly threatening towards the slavic peoples. For example another important trade agreement was signed on 20 March 1934. Furthermore, we know from the captured German documents that in 1935, 1936, 1937 and 1939 when Soviet and German officials held their routine economic meetings, the Soviet side suggested that it might be opportune to improve political relations. These suggestions were turned down by the Germans, but it is quite clear that Stalin was prepared to court the Nazis in secret, whilst espousing collective security (with France and Great Britain) in public. A final decision on which way to jump could be left until later, while the Soviet Union's ability to defend itself continued to grow.

This lead the USSR to move closer to the capitalist powers, although this was generally dissatisfying for Stalin. Time after time, the British and French chose not to stand firm in the face of aggressive moves by Italy, Japan or Germany, the three powers who had by 1937 created the Anti-Comintern Pact, which was clearly aimed at the USSR. The allies also tended to exclude the USSR from decision-making, with embassies in Britain taking on average several weeks to respond to Soviet telegrams, whereas British telegrams received a response in a few days. It was also excluded in the Munich agreement, despite having mutual assistance pacts with both France and Czechoslovakia as well as being in the League of Nations (having joined in 1934).

The Soviets also reaped considerable propaganda benefits from the Spanish Civil war. There is some debate as to why Stalin intervened in the war, but the three most prominent theories are generally considered to be:

• Preserve the democratically elected Republican government
• demonstrate his belief in collective security by helping to thwart fascist aggression
• show that the USSR was now an international force to be reckoned with.

The USSR gained propaganda value by intervening, as well as the unexpected bonus of the Spanish government's gold reserves, the famous Moscow Gold. More importantly, the three years of war gave him additional insights into the attitudes of his allies to be, France and Great Britain, his allies in terms of collective security, from which it was easy to determine that these allies would go to great lengths to avoid war. This added a layer of suspicion to Stalin's views of the intentions of his allies.

That pretty much covers everything before the war starts, if you have any questions, let me know. Sorry it's so long, you asked over quite a broad area so I didn't want to miss anything.