Why did relations between the USA and the Soviet Union worsen in the years 1947–49? Explain your answer

Firstly, its key to look at the relations between these two Superpowers, the US and Soviet Union, prior to 1947. The Grand Alliance during the Second World War resulted in a brief relaxation of tensions between the US and the Soviet Union; as they were more preoccupied on a common goal of defeating the Axis powers. However, as the Second World War ended it was clear that this alliance was just a mere matter of convenience and would not last much time in the post-war world. The two powers were very ideologically conflicting – the US advocated for a capitalist democracy, whereas the Soviet Union called for a Communist society. Tensions and suspicion were already visible in the post-war conferences, namely in the third and final conference – the Potsdam Conference (July-August 1945). In 1946, two key events occurred that increased the enmity between the Superpowers: Churchill’s Iron Curtain Speech (March 5, 1946) and the Kenan and Novikov Long Telegrams. The Churchill Iron Curtain Speech cemented the threat of the spread of the Soviet Union in Europe.  However, 1947 was a decisive year in mounting hostilities, especially taking into account the declaration of the Truman Doctrine (March 12, 1947) that thereby pronounced that it was the duty of the US to safeguard against the expansion of the Soviet Union. Clearly, the Truman Doctrine worked to greatly increase the enmity and tension – considering the American notion of ‘domino theory’ and thus their utmost need to contain the Soviet Union. The Marshal Plan later in 1948 further served to deteriorate the relations. The Marshal plan was American economic assistance to help rebuild post-war Western Europe, with over $12 billion coming from the US. Despite the US stating that it was acting in a defensive nature, the Soviet Union naturally saw all of this as offensive and aggressive foreign action, especially the Marshal Plan—thus responded with the Comecon in 1949. Comecon was the Soviet Union mutual economic assistance plan for the countries of Eastern Europe. It is also key to take into account, that another reason why those year worsened the US-Soviet Union relation was because it is when the so-called first military confrontation of the Cold War took place. The Berlin Blockade occurred between June 1948 and May 1949, and due to this US demonstration of being the ‘rescuing’ power and the Soviet Union being the ‘evil’ power, massively increased the enmity. The subsequent creation of West Germany in May 1949 very much angered the Soviet Union, as they would have wanted a united Germany and felt like the West, once again, was being aggressive towards her. Lastly, in August 1949 the Soviet Union also successfully developed nuclear weapons – so now the Americans felt vulnerable and threatened against the Soviet Union -- and this, therefore, worsened relations considering the highly destructive nature of the weapons. Based on this, it clear that between the years 1947-49 the events that occurred only served to reinforce and magnify the preexisting tension between the US and the Soviet Union. This peak of reactions from misunderstandings and mistrust merely served to deteriorate the relations between the two Superpowers and thereby introduce the Cold War to Europe!