Final answer:
The 'Western Allies' of Britain and the United States, whom the Soviets did not trust, were joining the war against Nazi Germany. The alliance was fraught with compromise and mistrust, given the complex history and conflicting postwar goals, leading to the formation of military alliances like the Warsaw Pact.
Step-by-step explanation:
The 'Western Allies' or 'Western world', namely Britain and the United States, whom the Soviets did not trust, were joining the war. These nations had complex and often conflicting interests during World War II, balancing the threat of Nazi Germany against the rise of the Soviet Union.
Historical accounts note that the Soviet Union suffered significant casualties during the war and recall the previous support given to the White Russians by the Allies against the Bolsheviks, indicating long-standing mistrust between the Soviets and the Western nations.