There are many different points of view about who was to blame for the Cold War.
Cold War is the term used to describe the state of conflict, tension and competition that existed between the United States and the Soviet Union (USSR) and their respective allies from the mid-1940s to the early 1990s.
On one hand, we can argue that USA was to blame for the Cold War. At the Yalta Conference, Roosevelt did not define well what he said about the “Sphere of Influence” (He mean that Germany have to be divided into 4 occupation zones). Stalin thinks about this and saw this as a total control over the East by the USA. In second place, another argument could be that USA tested the atomic bomb, and this cause tension between the USA and the USSR, because they feared that some of these 2 countries will drop a bomb some day. Finally, The Truman Doctrine (America sending money and supplies to a country in danger of a communist take-over) and the Marshall Aid (America giving money to prevent people to like communism) was seen as “Unfair” and made Stalin suspicious.
On the other hand, we can argue that the USSR was to blame for the Cold War. At Yalta Conference, Stalin wanted the border of the USSR to move westwards into Poland. Stalin argued that Poland could move its border westwards into German territory. Roosevelt first doesn’t accept this, but then he was convinced by Churchill. Secondly, another argument could be that Stalin did not take his troops out from Eastern Europe. People feared a communist take-over because of this. Also, after some time, he set up a communist government in Poland. Britain and USA protested. He said that his control of Eastern Europe was a defensive measure against possible future attacks. Furthermore, the Cominform (Communist Information Bureau) was set up to co-ordinate communist governments and industries. This was seen as a threat by the USA, as it exclude west.
In conclusion, we can argue that, although both countries had its arguments to be blamed for the Cold War, the USSR was to blame. USSR had take more powerful actions and its seemed that they wanted to start a war, because of Stalin’s armies occupying Eastern Europe and other reasons. In the Cold War, the friendship between the allies had broken down, and had been replaced by suspicion and accusation.