1953 

J. Robert Oppenheimer is accused of disloyalty and of communist contacts. President Dwight Eisenhower suspends his security clearance, and in a full hearing the following year he is not reinstated. While many scientists defended him, Edward Teller claimed Oppenheimer delayed working on the hydrogen bomb. In 1958 an AEC review finds the proceedings to be "a primitive abuse of the judicial system."

January
In his final State of the Union address, President Truman declares nuclear war impossible for "rational men."

March 5
Soviet leader Joseph Stalin dies.

March 17
Scientists study the impact of a nuclear blast on a fabricated American city during the test Annie at the Nevada Test Site. The test is part of Operation Cue, a series of projects conducted by the Federal Civil Defense Administration to evaluate the effects of nuclear detonations n civilian communities.

March 20
Nikita Khrushchev becomes first secretary of Communist party.

June 19
Julius and Ethel Rosenberg, sentenced as atomic spies in 1951, are executed by the U.S. [see March 29, 1951

June 26
Nikita Khrushchev authorizes arrest of Lavrentii Beria, head of the secret police and the Soviet bomb project.

July
In a Foreign Policy article U.S. physicist Robert Oppenheimer calls for greater openness in atomic policy debate.

July 27
Armistice is signed ending the war in Korea.

August
General Edmundson leads "Operation Big Stick." The mission requires him to take twenty B-36s, armed with nuclear weapons, to Okinawa in Japan.

August 8
Soviet Premier Georgi Malenkov announces that USSR possesses the hydrogen bomb. The development of the hydrogen bomb in the US and the Soviet Union is regarded as the start of the Cold War arms race.

August 12
The Soviet Union tests its first simple fusion bomb, Joe 4 , at the Semipalatinsk test site. The test is based on Andrei Sakharov's"Layer Cake."

November 7
Lawyer William L. Borden sends letter to FBI Director J. Edgar Hoover accusing Robert Oppenheimer [Oppenheimer Hearings] of being a Soviet spy.

December 3
President Dwight Eisenhower orders a "blank wall" be placed between Robert Oppenheimer [Oppenheimer Hearings] and atomic secrets.

December 8
President Dwight Eisenhower, in a United Nations address, proposes Atoms for Peace, a program to extend American aid to other countries for establishing nuclear reactors for peaceful research. Eisenhower calls for the nuclear weapons states to give part of their nuclear stockpiles to a United Nations-supervised "bank of fissionable materials" in an attempt to strip nuclear energy of "its military casing and adapt it to the arts of peace."

December 23
Atomic Energy Commission sends letter with charges to U.S. physicist Robert Oppenheimer [Oppenheimer Hearings].

Nikita Khrushchev authorizes the execution of Lavrentii Beria, the former head of Soviet secret police and the Soviet bomb project.