In 1945 the war had been fought on one side by the nations of Great Britain, USA and USSR, the members of the Grand Alliance achieved victory in WW2. It was more important than ever the victorious powers remained united as they faced the enormous task of reconstructing war torn Europe. However, as they sought to do this, their unity was already weakened by the existence of mistrust and suspicions between them. Despite the outward appearance of unity, these nations were fundamentally divided by their ideological rivalry which had already existed between them since 1917: the disagreements and strains they experienced; and their competing aims and ambitions for the future of post-war Europe on which their societies were based. The fundamental struggle between the communist system of USSR and capitalist ideas of USA and Great Britain ideological rivalry is evident to be the most significant explanation for the existence of mistrust and suspicion between them. Due to the fact, it lies at the basis of the other casual factors.
The long term issues of their ideological rivalry which was present between the USSR and the West since the Bolshevik Revolution in 1917 was a significant contributory factor in the development of a hostile relationship between them. The great power rivalry was evident during the years of 1917 to 1941; the Bolshevik Revolution in 1917 saw the rise of Lenin which meant a rise in Communism. It can be said the Soviet foreign policy was driven by communist ideology rather than national security. This was a threat of a totalitarian state. Ideology of Marxism was alien to the USA as left wing politics were unheard of; this was especially threatening as Marxist ideology saw the destruction of capitalist societies such as the USA. Its egalitarian values and its attacks on the freedoms held to be so important in a Liberal Democracy.