The Russian civil war lasted from 1918 to 1920 and was fought between the Bolsheviks and the White army. The white army were helped by the Western countries including Britain, America and France. By 1920 there were 250,000 foreign troops on Russian soil trying to prevent the spread of Communism and defeat the Bolsheviks.
The western countries were concerned massively about the large amounts of military equipment that the Bolsheviks were using and this was another reason why they helped the White army.
This increased tensions because it clearly showed the Bolsheviks what side the western countries were on and how they could never truly trust the Western countries again because it showed the differences in ideologies the West and Eastern countries had.