1947

April 17
US Atomic Energy Commission issues a memo on "Medical Experiments on Humans." It reads in part, "It is desired that no document be released which refers to experiments with humans and might have adverse effect on public opinion or result in legal suits. Documents covering such work field should be classified 'secret'."

June 5
U.S. Secretary of State George Marshall announces European Recovery Program, a.k.a. Marshall Plan. 

July
George F. Kennan , U.S. Chargé d'affaires in Moscow, outlines policy of political containment of Soviet Union.

August
The United Kingdom's first atomic reactor at Harwell comes into operation.

September 28
British physicist Klaus Fuchs meets with his agent Alexander Feklisov in London and describes certain structural characteristics of the hydrogen bomb.

October
Nuclear war plans of U.S. Joint Chiefs of Staff considers 150 "Nagasaki type" sufficient to defeat the USSR. Nuclear weapons stockpile is still small (20-50) but growing.