Russia and the prohibition on threatening to use nuclear weapons

By Stuart Casey Maslen, Extraordinary Professor, Centre for Human Rights, University of Pretoria, South Africa

In its 1986 Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, the International Court of Justice made it clear that a threat to use force for an unlawful purpose was itself unlawful. The prohibition of aggression is a peremptory norm of international law, and any threat or use of force in the execution of a war of aggression is thus inherently unlawful. Indeed, in Paragraph 47 of the 1996 Advisory Opinion, the Court gave the example of efforts to secure territory by dint of threatened force as being a violation of Article 2(4) of the UN Charter (and customary law). That Russia is engaged in ongoing aggression in Ukraine is beyond doubt of fact and law.

Thus, when Russia’s president, Vladimir Putin, said on 21 September that “all means available” would be used to secure the territorial integrity of Russia (implicitly including territory seized in Ukraine), this was a clear violation of the UN Charter. This is because the threat was clearly intended to support a war of aggression and the annexation of foreign territory.

Whose utterances matter?

But there is another issue that was unexplored in the 1986 Advisory Opinion: whose utterances are relevant and determinant in any assessment of a declared threat of force? For sure, it is not anyone in a State that has the power to order force to be used. In order to constitute a threat of force under international law, a statement must be credible in the circumstances. This means that the threat must emanate from a person or an authority in a position to either effect or direct the use of force, and in this context the use of a nuclear weapon. Ordinarily, it is the functional (not nominal) head of the Executive branch (the president or prime minister, depending on the Constitution), along with the Minister of Defence, and oftentimes the national parliament (when authorising the threat or use of force).

Which brings us back to Mr Medvedev. Since 2020, when President Vladimir Putin forced him to resign as prime minister, he has been the deputy chair of Russia’s Security Council. This is a purely consultative position under the Constitution. He can make bellicose statements all day long (as can anyone with a Twitter account or a blog), but he has no influence on whether Putin ultimately decides to go nuclear and lead the world down an even darker path than the one already taken. Mr Medvedev’s statements do not therefore amount to a threat of force under international law. The tragedy is that in these febrile times his statements nevertheless contribute to a heightening of tensions and potentially even normalise the possibility of use of nuclear weapons, increasing thereby the risk of nuclear calamity.

Treaty on the Prohibition of Nuclear Weapons

Article 1(1)(c) of the Treaty on the Prohibition of Nuclear Weapons (TPNW) makes threatening to use nuclear weapons a core prohibition at all times, and regardless of whether use would itself be a violation of international law or in legitimate self-defence against foreign aggression. It is therefore broader in scope than the prohibition on threat of force in Article 2(4) of the UN Charter.

A case in point is a statement made by the French Minister for Europe and Foreign Affairs, Jean-Yves Le Drian, in response to Putin’s order to heighten the state of alertness of Russia’s nuclear forces in February 2022. Le Drian stated that “Vladimir Putin must also understand that the Atlantic alliance is a nuclear alliance”. Since this was a reference to use in self-defence, it did not contradict the UN Charter but nevertheless amounted to threatening to use nuclear weapons as prohibited under the TPNW.

Neither France nor Russia is a State Party to the 2017 UN Treaty and both have no intention of joining it, but it is a useful exercise in understanding the scope of the provision to consider how recent statements would be compatible with the norm in subparagraph (c) of Article 1(1). Under the TPNW, only the utterances of persons or authorities in a position to either effect or direct the use of nuclear weapons can amount to prohibited threats of use. Thus, while President Putin’s statement on 21 September constituted a threat to use nuclear weapons under the TPNW, Medvedev’s statement on 27 September did not.

Implicit and explicit threats

Prohibited threats under the TPNW may be implicit as well as explicit. A stated threat does not, therefore have to refer to use of nuclear weapons, although it would be more likely to violate the norm in the TPNW should it do so. Putin’s statement on 21 September did not mention the use of nuclear weapons, specifically, only “all means available” and “weapons of destruction”, but it was clear from the context that he was referring also to nuclear weapons.

In certain circumstances of tension, such as the ongoing Ukraine conflict, a show of force by means of missile testing, an explosive test of a nuclear weapons, a military exercise involving possible use of nuclear weapons, or a nuclear strike exercise, could also amount to unlawfully threatening to use nuclear weapons under the TPNW (along with other violations of the Treaty).

Possession

Some argue that possession of nuclear weapons and policies of nuclear “deterrence” are per se a threat of force under the UN Charter and a threat to use nuclear weapons under the TPNW, but they are mistaken. It is true that the International Court of Justice’s remarks in this regard in 1986 were a little opaque: “Possession of nuclear weapons may indeed justify an inference of preparedness to use them.” But this is true of any State having an army equipped with any weapons. As the Court later explains, it is the intended use of force that is adjudged illegal or legal, not their mere possession.

Possession of nuclear weapons and the broader concept of nuclear deterrence, where the threat to use nuclear weapons is not specific in nature, are also not sufficient in themselves to constitute threatening to use under the TPNW. Nuclear deterrence practices are, however, illegal under the Treaty’s Article 1(1)(a), which prohibits possession and stockpiling of nuclear weapons.