The Limited Test Ban Treaty (LTBT) is a treaty prohibiting all test detonations of nuclear weapons except underground. It was developed both to slow the arms race (nuclear testing was, at the time, necessary for continued developments in nuclear weapons), and to stop the excessive release of nuclear fallout into the planet's atmosphere. The Treaty was signed and ratified by the governments of the Soviet Union, the United Kingdom, and the United States during the autumn of 1963.

It is officially known as the treaty banning nuclear weapon tests in the atmosphere, in outer space and under water, but is often abbreviated as the Partial Test Ban Treaty (PTBT), Limited Test Ban Treaty (LTBT), or Nuclear Test Ban Treaty (NTBT) – although the latter also refers to the Comprehensive Test Ban Treaty. The Treaty was signed by the governments of the U.S.S.R.(represented by Andrei Gromyko), the United Kingdom (represented by Alec Douglas-Home), and the United States (represented by Dean Rusk), named the "Original Parties", in Moscow on August 5, 1963, before being opened for signature by other countries. The Treaty of Moscow was ratified by the U.S. Senate on September 24, 1963, by a vote of 80 to 19. The treaty went into effect on October 10, 1963.