<P> The Origins of the Cold War involved the breakdown of relations between the Soviet Union versus the United States , Great Britain and their allies in the years 1945 -- 1949 . From the American - British perspective , first came diplomatic confrontations stretching back decades , followed by the issue of political boundaries in Central Europe and political non-democratic control of the East by the Soviet Army . Then came economic issues ( especially the Marshall Plan ) and then the first major military confrontation , with a threat of a hot war , in the Berlin Blockade of 1948 -- 1949 . By 1949 , the lines were sharply drawn and the Cold War was largely in place in Europe . Outside Europe , the starting points vary in the late 1940s or early 1950s . </P>
when did the cold war alignment of britain and the united states versus the soviet union begin
1945