Creating an international norm prohibiting nuclear threats and use against non-nuclear states

Russian President Vladimir Putin stated in a September 2022 public address that Russia had “various weapons of destruction” and would “use all means available to [them].”  Many understood this to be a threat to use nuclear weapons in Ukraine. The world was shocked and horrified. However, neither this threat nor the actual detonation of a nuclear weapon would clearly violate any established norm of international law.

It is long past time to establish a legal universal norm, by treaty or by UN Security Council (UNSC) action, that makes the threat or use of a nuclear weapon against a state which has committed by treaty not to possess nuclear weapons, and which is also honoring that commitment, a war crime. States parties to the agreement would commit themselves to come to the aid of a state which is subject to attack by all means necessary, including by providing urgent consultation and military support, if deemed critical. In the event of a threat to use nuclear weapons, states would consult and take steps to make clear that if the threat is carried out, they will respond as the United States did in response to Putin’s threat when President Biden warned of “catastrophic consequences.”

When the United States and the Soviet Union began negotiating the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) in the 1960s, both governments and most observers assumed that negative and positive security assurances would need to be part of the agreement. Surely, in addition to commitments to negotiate nuclear disarmament and to the sharing of peaceful nuclear activity, any state asked to give up its right to develop nuclear weapons would insist that those states allowed to retain nuclear weapons commit not to threaten or use nuclear weapons against states giving up that right. Those states would also insist that the nuclear parties promise to come to their aid if there was such a threat or use of nuclear weapons.

In the end, neither negative nor positive security assurances for non-nuclear states were incorporated in the NPT.

The Soviet Union and the United States issued parallel non-binding statements of an intent to come to the aid of any non-nuclear state in good standing under the NPT and subject to a nuclear attack. A UNSC Resolution of June 19, 1968, welcomed the “intention expressed by certain states” to provide immediate assistance to a state that adheres to the NPT and is a victim of aggression “in which nuclear weapons are used.”

The significance of the American commitment was further reduced when the Senate, in giving consent to ratification of the NPT, asserted that it implied no commitment by the United States beyond the treaty commitments it already had. President Richard Nixon, who inherited the treaty from President Lydon Johnson and who was tempted to walk away from it, made it clear that he agreed with the Senate.

Neither the United States nor the Soviet Union issued any sort of negative security assurance—that is, any commitment not to threaten or use nuclear weapons against non-nuclear states party to the NPT. Early in the negotiations, the two lead states ruled out binding treaty language, but they exchanged drafts of a possible statement that they would each issue separately. The Soviet Union proposed language offering not to threaten or use nuclear weapons against a non-nuclear state unless the state permitted a nuclear power to store nuclear weapons on its territory.  This language, which sought to put pressure on Germany to insist that the United States remove its nuclear weapons from German territory, was unacceptable to the United States and its NATO allies.

The American proposal would have stated that the “United States affirms its intention to refrain from the threat or use of nuclear weapons against any non-nuclear weapon state, party to the treaty on the non-proliferation of nuclear weapons that is not engaged in an armed attack assisted by a nuclear weapon state” (1). This language was understood to be aimed at the Warsaw Pact and North Korea. When given to the Soviets in private negotiations, it was summarily rejected. The American language was not made public at that time.

The NPT Treaty was signed, ratified, and went into effect without real positive or negative security assurances.

In 1995, the state parties to the NPT revisited the issue of negative security assurances in the context of Article X.2 of the treaty which provides that “[t]wenty-five years after the entry into force of the Treaty, a conference shall be convened to decide whether the Treaty shall continue in force indefinitely, or shall be extended for an additional fixed period or periods. This decision shall be taken by a majority of the Parties to the Treaty.”

The non-nuclear parties to the treaty pressed hard for a negative security assurance from the five nuclear powers, by then all parties to the NPT, which would be uniform, unconditional, and legally binding.  The nuclear powers, who are also the five permanent members of the Security Council, responded by consulting with each other. Each then issued a statement providing a negative security assurance. Then they jointly sponsored a resolution, passed unanimously by the UNSC, which “takes note with appreciation of the statements made by each of the nuclear weapons states in which they give security assurances against the use of nuclear weapons to non-nuclear weapons states” that are parties to the NPT.

Regrettably, the statements fell far short of the objective stated by the non-nuclear weapons states that the assurances be unconditional, uniform, and binding. None of the commitments were legally binding. Only the Chinese statement, reiterating a long-standing PRC position, was unconditional, declaring that “China undertakes not to use or threaten to use nuclear weapons against non-nuclear weapon states…at any time or under any circumstances.” The other four powers issued statements which exempted from its assurance the case of an attack on them by a non-nuclear state allied with a nuclear power. The statements marked some progress. No state exempted a state using chemical or biological weapons, and the Soviet Union did not exclude states with nuclear weapons on their territory.

American presidents have issued unilateral negative security assurances culminating in the Obama pledge not to threaten or use nuclear weapons against non-nuclear states that are a party to the NPT and “in compliance with their nuclear non-proliferation obligations.” President Biden reiterated this commitment making no exception for attacks by a state allied with a nuclear power.

The global response to the Russian threat to use nuclear weapons against Ukraine suggests that now is the moment to codify negative and positive security assurances as a matter of international law, either by amending the NPT or through a binding UNSC resolution and with a standard that is uniform, unconditional, and legally binding.

If the UNSC acted, it could simply declare that it is a violation of the Charter and of international law for a state possessing nuclear weapons to threaten or use a nuclear weapon against a state which is a non-nuclear member in good standing of the NPT. The Secretary General would be charged to monitor the possibility of such a threat or use and to bring the matter urgently to the attention of the Council.  States would be invited to indicate their intention to respond collectively and effectively to any such threat or use.

Providing such assurances would strengthen the NPT and help persuade states not to exercise the right of withdrawal. It would also contribute to strengthening the global norm against threats of nuclear detonations and nuclear explosions.

(1) Morton H. Halperin, If Only You Do Not Want the Credit: A Washington Memoir, Forthcoming. Documents available from the author.

Morton H. Halperin is Chair of the CERL Executive Board. He worked on nuclear policy issues in the Clinton, Nixon, Johnson, and Kennedy administrations. Dr. Halperin held a number of senior positions in the government including as Director of the Policy Planning Staff at the Department of State (1998-2001). He taught at Harvard (1960-66) and as a visitor at other universities including Columbia, George Washington, and Yale.

He has been affiliated with a number of think tanks including the Center for American Progress, the Council on Foreign Relations, the Carnegie Endowment for International Peace, the Century Foundation, and the Brookings Institution. He has testified often before congressional committees including on the New START Treaty and U.S. nuclear policy. Dr. Halperin served on the Congressional Commission on the Strategic Posture of the United States.

Dr. Halperin is the author and co-author of numerous books and articles on nuclear policy including Limited War in the Nuclear AgeStrategy and Arms ControlChina and the Bomb, and Nuclear Fallacy.

The views expressed here are those of the author and do not necessarily represent CERL’s official views.

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