October 10, 1963

Partial Nuclear Test Ban Treaty

Partial Nuclear Test Ban Treaty enters into force

Ratification papers changed hands in three capitals on the same day. Kennedy had signed the American instrument only three days earlier.

Three capitals, one day

The treaty entered into force on 10 October 1963, once the United States, United Kingdom and Soviet Union had deposited their instruments of ratification with the three depositary governments. Article III made those three ratifications the condition.

Instruments were exchanged in corresponding ceremonies in Washington, London and Moscow.

Kennedy had signed the U.S. instrument on 7 October, after the Senate consented 80–19 on 24 September, and he proclaimed the treaty on the 10th.

What the parties gave up

From that day the original parties were legally bound not to conduct nuclear explosions in the atmosphere, in outer space or underwater.

The prohibition also reached explosions anywhere else if radioactive debris crossed the testing state's borders.

This was a partial ban. Some contained underground testing remained outside it.

Not a permission slip for underground tests

The treaty did not authorize underground testing. Such tests fell outside the ban only where their radioactive debris stayed within the testing state's territorial limits.

It also is not the Comprehensive Nuclear-Test-Ban Treaty, which came much later.

The 10 October date belongs to entry into force; the signing had taken place in Moscow on 5 August 1963.

Sources

Researched 24 Aug 2026 4 sources not yet audited

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