They became suspicious of each other because they had different beliefs; the USSR was a Communist country, ruled by Josef Stalin, a cruel dictator, who didn't really care too much for human rights - of the world or his own people! Whereas the USA had a capitalist democracy which considered freedom as a great and essential value. Each hated the other's democracy and believed that the other wanted to destroy their democracy. For example, with the creation of an atom bomb, the Stalin got really nervous as they believed that this weapon would be the one that would end them and communism in Russia whereas President Truman believed that the Redy Army was being trained to kill Americans! This difference in lifestyle caused a lot of turbulence between the superpowers; it caused suspicion of motives and actions. The two sides had this turbulence because of a lack for understanding - they believed that their democracy was the only way to go with and would be rigid to change! They had an aim: to prove to the world that their way was superior, again causing them to provoke confrontation.
These beliefs that they had, in turn, led towards creating the Cold War.
History also had it's part to play, both sides absolutely resented their history, causing furthering their suspicion. It was hard for the USSR to forget that in 1918, the UK and USA joined forced to try and prevent the Russian Revolution. Stalin also believed that more could be done to help his Russia in the Second World War; he constantly cried out for help but there was no response, he believed that they were deliberately turning a blind eye towards then due to their communist beliefs. However, on the other hand, Britain and the USA had not forgotten about the Nazi-Soviet Pact with Germany in 1939! History also caused a great deal of hatred between the sides not to mention suspicion. It is possible that revenge was an element in all of this! Another disagreement from history was the division of Germany and reparations. The US felt no need for them, as the US wanted Germany to recover economically. Roosevelt provided uncertain direction about this issue, and believed this difficult political decision should be taken after the war! Roosevelt did admit that reparations could hardly be denied the Soviets after the damage they had suffered. These events also helped cause the Cold War.
Both the USA and the USSR had very different aims. Stalin wanted to maintain his 'sphere of influence' over the whole of Eastern Europe, this was because of the immense amount of damage they occurred during WWII, they wanted to prevent invasion upon them happening again. He wanted huge sums of the reparation from Germany. He stripped the Soviet part of Eastern Germany of all wealth, agriculture and industry. This was opposed by Britain and the USA as they thought it was just Stalin's way of tightening his grip upon Germany! Both the UK and the USA found it necessary to protect democracy and also to help Germany recover. They knew that huge sums of land were falling to communism, most of Europe was under Stalin's control! Stalin argued that the UK and USA were simply setting Germany up again for another attack upon the USSR!Finally, because neither side trusted each other, events made them hatre each other more:-The Yalta Conference of February 1945 caused problems because, regardless of the fact that it seemed successful, tension grew from it! After the conference Churchill sent to Roosevelt 'The Soviet union has become a danger to the free world.'-The Potsdam Conference of July 1945, all of the arguments became open; the USSR and America, in plain sight, argued over how to divide Germany, the reparations necessary as well as the Soviet take-over in Poland.
-The Soviet Salami Tactics during 1945-48 caused suspicion - although Russia claimed that they only wanted to create 'bumpers' between themselves and Germany, the western powers believed the USSR was, instead, building an empire of the eastern world. At Fulton Churchill spoke about the iron curtain cutting off east from west. Behind this, he said, the people of easter Europe were 'subject to Soviet influenceÃ¢ÂÂ¦totalitarian control and police governments'.
So, to conclude, the superpowers became suspicious of each other by the Fulton speech in 1946 because of beliefs and turbulence between communism and capitalism, because of history, such as the building of the atomic bomb and the red army, because of aims such as the promote and deploy a 'sphere of influence' and because of the events taking play in the Yalta and Potsdam Conferences, as well as the Salami TacticsWalsh GCSE Modern History Textbookhttp://www.johndclare.net/EC2.htmModel Essay from this link