The orthodox school sees the Cold War as the product of the aggressive and expansionist foreign policies of USSR. This view has been presented by historians such as W. H .McNeill, H. Feis, and A. Schlesinger.
After WW2 a power vacuum was left in a large part of central and Eastern Europe. Stalin took the advantage of this in order to strengthen the Soviet Union and spread communism. In the Yalta conference (Feb 1945), Stalin demanded parts of Poland to be given to USSR. Stalin made a communist government of Poland although there was already a Polish government in UK. This kind of behavior made the West (USA, UK etc) fear that USSR would gain permanent control over Poland. Stalin went even further, in the same year (1945 July~August) Potsdam conference, Stalin wanted parts of Turkey, demanded trusteeship of one of the former Italian colonies in Africa, disabled USA and allies access in areas of Europe occupied by the Red Army, moved the frontier of the USSR westwards and gave Poland lands that the allies didn’t agree. Stalin’s actions and his wants made the West think Stalin was trying to make a huge communist empire. This marked a cooling in relations between the two sides.
Between 1945 and 1948 communist regimes were established throughout Eastern Europe (Salami tactics). Albania (1945), Bulgaria (1945), Poland (1947), Hungary (1947), Romania (1945-1947), Czechoslovakia (1948), and East Germany (1949), all these countries went through a different process, but the results were the same. The Red Army retained a presence in much of Eastern Europe during and after this process. A ‘communist zone’ was created in Europe. This was seen as yet another example of Stalin’s expansionist foreign policy. The Berlin blockade could be another example, 24th June 1948; Stalin closed all rail and road links from Berlin to West supplies. The west saw this as an attempt to starve the west out of the city as a prelude to a possible attack on West Germany. It was defeated in 12th may 1949, only by the west’s airlift of all supplies into the western sector of the city. In result, NATO was created in 1949 by the Western Allies as a defensive alliance against the USSR.
March 1946, Churchill’s Fulton speech described the Soviet bloc as an ‘iron curtain’. Stalin believed this was necessary to maintain the safety of the USSR. The tension worsened all the time. For example, March 1947 Truman Doctrine, The US implemented a policy of ‘containment’ towards the USSR, and this is the evidence of the increased tension between the two superpowers.
By the end of 1949, East Europe was in the hands of USSR. The Communist states installed by Stalin were controlled by two organizations. One of them was Cominform (replacement of comintern) coordinated and ensured that communist parties over East Europe prevailed Soviet style communism. The other was Comecon, which coordinated the economies of their communist states. The movement of spreading of communism also started to show in the Far East. The victory of the Chinese communist party and the invasion of South Korea by the communist North Korea were viewed by the West as the evidence that Stalin’s expansionist policies have secured the spreading of communism.
Although these actions were reasonable in the Soviet point of view, most of Stalin’s actions were offensive towards the West Alliance in the US point of view. The conflict’s outbreak was in part a consequence of the Western powers’ failure to accommodate Soviet security needs, but this very failure stemmed from Soviet policies. Stalin’s policies were too aggressive in the West point of view, and were unacceptable. Thus the Soviet foreign policies were quite responsible for the outbreak of the Cold War.