Immediately after the Second World War, Germany had been divided into British, French, American and Russian zones. Britain, suspicious of Russian intentions in Eastern Europe, found itself at odds with Russia. In 1946 Winston Churchill famously spoke of an 'iron curtain' dividing Europe between the communist east and the democratic west.
Since Greek occupation in 1944, Britain had assisted the Voulgaris Government with military and economic aid, against the Soviet-supported Greek People's Liberation Army (ELAS). In the financial crisis of 1947 the cost of maintaining the Greek government became too much, and in February 1947 Britain announced an end to funding.
During 1946 the US did not regard Russia as a serious threat, but the withdrawal of British financial support for Greece provoked fears about the spread of communism in Europe. There was increasing tension as the US opposed the excessive extraction of reparations from Germany. A bill was passed giving US military support and economic aid to Greece. This was the beginning of the 'Truman Doctrine' - an approach to containment of communism and Soviet growth named after US President Harry Truman.
The US Secretary of State, George C. Marshall, appalled by evidence of economic decline, feared the rise of communism. Calling for active promotion of economic recovery in Western Europe, he invited countries to put forward their dollar requirements. A European Recovery Act was passed in 1948. Russia, strengthening its grip on Eastern European countries, ensured that Poland and Czechoslovakia refused the American offer. The Marshall Plan polarised Europe into western and communist blocs.