Treaty between the United States of America and the Union of Soviet Socialist Republics on Underground Nuclear Explosions for Peaceful Purposes (PNE Treaty)


  • Signed: 28 May 1976
  • Entered into Force: 11 December 1990
  • States Parties: United States and Soviet Union
  • Duration: Five years with automatic extension for successive five-year periods unless either State Party notifies the other of its termination. Neither Party, however, may withdraw from the treaty, while the Threshold Test Ban Treaty (TTBT) is in force.


During the negotiations of the TTBT, the United States and Soviet Union recognized the need to agree on appropriate measures related to peaceful nuclear explosions (PNE). Under Article III of the TTBT signed in June 1974, the States Parties undertook to negotiate and conclude, at the earliest possible time, an agreement governing underground nuclear explosions for peaceful purposes. On 7 October 1974, the negotiations on the PNE Treaty began in Moscow, and after 18 months of negotiations, were completed in April 1976. The PNE Treaty was signed on 28 May 1976.

Scope of Application

The treaty applies to all nuclear explosions for peaceful purposes conducted by the Parties after 31 March 1976 outside the geographical boundaries of test sites specified under the TTBT.


The treaty gives the Parties the right to conduct underground PNEs at any place under their jurisdiction or control outside the geographical boundaries of test sites specified under the TTBT and to carry out, participate in, or assist in carrying out underground PNEs in the territory of another State at the request of such other State. The Parties undertake, however, not to conduct individual underground PNEs with a yield exceeding 150 kilotons, group underground PNEs with an aggregate yield exceeding 1.5 megatons, or group PNEs with an aggregate yield exceeding 150 kilotons unless the individual explosions in the group could be identified and measured by agreed verification procedures. The treaty establishes a Joint Consultative Commission to facilitate the treaty's implementation, and to handle issues of information exchange, compliance, and changes in technology that might have a bearing on the Treaty's provisions, and consider possible amendments to the treaty.

Agreed Statement

The treaty is accompanied by the Agreed Statement, which specifies that PNEs will not be used for developmental testing of nuclear explosive, and will not involve test facilities, instrumentation, or procedures related only to testing of nuclear weapons or their effects.

Verification and Compliance


The Treaty entitles the parties to use their national technical means (NTM) of verification and provide each other with information and access to sites of PNEs, in accordance with the Protocol, to ensure compliance with the Treaty. The parties commit not to interfere with NTM. The initial Protocol to the Treaty specifies details for the PNEs and provides for the exchange of detailed information about the explosions before and after. The Protocol entitles the parties to conduct visits by their designated personnel to the other party's designated areas and locations in case of PNEs with a yield exceeding 100 kilotons. The Protocol regulates the designated personnel's rights, functions, and equipment.

Enhanced Verification

In 1987, after a series of six-round negotiations, the United States and the USSR agreed to revise the PNE Treaty Protocol to include more effective verification provisions. Another series of six-round talks, which took place between 1987 and 1990, resulted in the signing in June 1990 of a new Protocol that provides for an enhanced regime of verification. The new Protocol replaced the initially agreed upon Protocol, and elaborates on its provisions. For the purpose of verification of compliance with the Treaty, the new Protocol gives the parties the right to use the hydrodynamic yield measurement method and a local seismic network in the case of a PNE with a yield exceeding 50 kilotons. In the case of a PNE with a yield exceeding 35 kilotons, the parties are entitled to conduct on-site inspections. All the notifications required by the Protocol and other relevant information are to be transmitted through the Nuclear Risk Reduction Centers (NRRC), established in 1987 in the United States and Soviet Union to reduce the risk of conflict or of accidental nuclear war between the two countries. On-site inspections are to be conducted to confirm the validity of the geological and geophysical information and other relevant information, to observe the emplacement of each explosive canister, to observe the explosion, etc. The 1990 Protocol specified functions and rights of on-site inspection teams.


A Joint Consultative Commission was established to make inquiries and furnish information, to assure confidence in compliance with the obligations to consider questions concerning compliance with the obligations, assumed and related situations that may be considered ambiguous, and to consider questions involving unintended interference with the means for assuring compliance with the provisions of this Treaty.

The treaty entered into effect on 11 December 1990. Since the treaty's entry into force, neither Party has conducted a PNE. Article V of the Nuclear Non-Proliferation Treaty (NPT) allows for PNEs. However, the States Parties to the NPT agreed at the 2000 NPT Review Conference that Article V of was to be interpreted in the light of the Comprehensive Nuclear Test Ban Treaty (CTBT), once it enters into force. Although the CTBT was signed in 1996, it has not yet entered into force.


The PNE Treaty allows the United States and the USSR to conduct underground peaceful nuclear explosions at any location under their jurisdiction or control.

This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents. Copyright 2019.