<P> Various events before the Second World War demonstrated the mutual distrust and suspicion between the Western powers and the Soviet Union, apart from the general philosophical challenge that communism posed towards capitalism . There was Western support of the anti-Bolshevik White movement in the Russian Civil War, the Soviet funding of the 1926 United Kingdom general strike causing Britain to break relations with the Soviet Union, Stalin's 1927 declaration of peaceful coexistence with capitalist countries "receding into the past," conspiratorial allegations during the 1928 Shakhty show trial of a planned British - and French - led coup d'état, the American refusal to recognize the Soviet Union until 1933 and the Stalinist Moscow Trials of the Great Purge, with allegations of British, French, Japanese and Nazi German espionage . However, both the US and the USSR were generally isolationist between the two world wars . </P> <P> The Soviet Union initially signed a non-aggression pact with Nazi Germany in August 1939 . But after the German Army invaded the Soviet Union in June 1941 and the Japanese bombed Pearl Harbor in December 1941, the Soviet Union and the Allied powers formed an alliance of convenience . Britain signed a formal alliance and the United States made an informal agreement . In wartime, the United States supplied both Britain and the Soviets through its Lend - Lease Program . However, Stalin remained highly suspicious and he believed that the British and the Americans had conspired to ensure that the Soviets bore the brunt of the fighting against Nazi Germany . According to this view, the Western Allies had deliberately delayed opening a second anti-German front in order to step in at the last minute and shape the peace settlement . Thus, Soviet perceptions of the West left a strong undercurrent of tension and hostility between the Allied powers . </P> <P> The Allies disagreed about how the European map should look, and how borders would be drawn, following the war . Each side held dissimilar ideas regarding the establishment and maintenance of post-war security . The western Allies desired a security system in which democratic governments were established as widely as possible, permitting countries to peacefully resolve differences through international organizations . </P> <P> The Soviet Union sought to dominate the internal affairs of countries that bordered it . During the war, Stalin had created special training centers for communists from different countries so that they could set up secret police forces loyal to Moscow as soon as the Red Army took control . Soviet agents took control of the media, especially radio; they quickly harassed and then banned all independent civic institutions, from youth groups to schools, churches and rival political parties . Stalin also sought continued peace with Britain and the United States, hoping to focus on internal reconstruction and economic growth . </P>

What was the background of the cold war