The Theatre Nuclear Weapons Treaty (TNWT) is an international treaty whose objective is to limit the range and payload of nuclear weapons, as well as limiting the number of states which can possess nuclear weapons, with the intent of preventing nuclear war. The treaty also establishes guidelines for the peaceful use of nuclear power in all signatory states.
Almost every sovereign state in the world has signed and ratified the TNWT, including the six Nuclear Weapons States outlined in the treaty: Britain, the UAPR, Canada, France, the ROC and the PRC. More countries have ratified the TNWT than any other arms limitation and disarmament agreement, a testament to the Treaty's significance.
At least one non-party to the treaty, the Soviet Union, is believed to possess nuclear weapons, though the Soviet government operates under a policy of opacity regarding its nuclear weapons program. Libya and South Africa are believed to have previously had nuclear weapons programs, though they have signed the treaty and no evidence of such a program has been found since 1990.
The main body of the TNWT is devoted to preventing the construction and use of ballistic missiles by signatories, especially intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs). The TNWT also limits the maximum yield of nuclear weapons to 100 kilotons TNT equivalent, partly in response to nuclear accidents such as the Easy Dog nuclear test. Additionally, the treaty limits the possession of nuclear weapons to the six recognized Nuclear Weapons States, with rules for the use of nuclear power for civilian purposes by these and any other states.
The Theatre Nuclear Weapons Treaty is considered to have been successful, as none of the recognized nuclear powers are known to have any nuclear weapon larger than a cruise missile, and only one other state is suspected of having nuclear weapons. Critics of the TNWT argue that the treaty would be ineffective in stopping states from developing nuclear weapons if such a program was initiated.