The prohibition on threatening to use
The Nuclear Weapons Ban Monitor found that two states acted in contravention of the Treaty on the Prohibition of Nuclear Weapons’ (TPNW) prohibition on threatening to use nuclear weapons in 2024: North Korea and Russia. North Korea overtly threatened to use nuclear weapons against South Korea while Russia implicitly threatened to use nuclear weapons against Ukraine.
At the start of 2024, North Korean leader Kim Jong Un said his country would no longer pursue reconciliation with the South and instead described South Korea as the North’s ‘principal enemy’ and threatened to ‘thoroughly annihilate’ the United States and South Korea if provoked. This is a specific threat to use nuclear weapons going beyond the notion of nuclear deterrence. Indeed, Robert A. Manning, a distinguished fellow with the Strategic Foresight Hub at the Stimson Center and experienced commentator on North Korea, wrote in October that ‘the Korean Peninsula seems more dangerous and volatile than at any time since 1950’.
Following the victory of Donald Trump in the US presidential election, the North Korean leader renewed his call for a ‘limitless’ expansion of his nuclear programme to counter US-led threats. Any new nuclear test by North Korea would not only violate the prohibition on testing in Article 1(1)(a) of the TPNW but, given the bellicose circumstances in which such testing would be occurring, this would also be likely to amount to threatening to use nuclear weapons under Article 1(1)(d) of the Treaty. As set forth in the interpretation of this provision above, and consonant with international law, conduct other than verbal threats may constitute a threat of the use of nuclear weapons.
Russia
In an effort to reinforce the credibility of Russia’s nuclear deterrence, Russian President Vladimir Putin authorised a change in Russian nuclear doctrine (called Russia’s Basic Principles of State Policy on Nuclear Deterrence) on 19 November 2024. When combined with the use against Ukraine two days later of a new hypersonic, intermediate-range, nuclear-capable missile, this amounted to an implicit threat to use nuclear weapons against Ukraine. The timing of the launch of the new policy was also of significance, coming just days after the Biden administration allowed Ukraine to fire missiles supplied by the United States into Russia for the first time.
The updated nuclear doctrine, which was published on the Kremlin website, diverges in two important ways from the earlier iteration in 2020. First, it raises the possibility that nuclear weapons could be used against a nuclear-armed nation that does not directly launch an attack on Russia but which supports such an attack by a non-nuclear country. As The New York Times reports, ‘That is a clear reference to Ukraine and its nuclear-armed backers, led by the United States. Russia’s previous nuclear doctrine focused on responding to attacks by nuclear-armed countries and alliances.’ Second, the new policy lowers the threshold at which Russia could consider the use of nuclear weapons in response to an attack using conventional weapons. The previous doctrine said such an attack must threaten ‘the very existence of the state’, while the new policy only requires a ‘critical threat’ to Russia’s sovereignty.
On 21 November 2024, Russia then fired into Ukraine a new intermediate-range, nuclear-capable missile that is believed to be close to production at scale. The Oreshnik has multiple (believed to be between six and eight) warheads that are independently targetable – a capability inextricably linked with nuclear missiles. The hypersonic missile, which is claimed to travel at some 8,000 miles per hour, would have been unlawful under the now-defunct 1987 Intermediate Nuclear Forces (INF) Treaty.
The Oreshnik missile appears to have been fired in a lofted trajectory in order to reduce range. A former Kremlin advisor, Sergei Markov, told Reuters the use of the weapon was ‘symbolic’, sending a message from Putin to the West: ‘Back off!’ It hit the central city of Dnipro, and seemingly targeted an aerospace manufacturing plant. Russia gave the United States advance warning of the missile strike on Dnipro ‘through nuclear risk reduction channels’ some thirty minutes before the attack, according to the US Department of Defense’s Deputy Spokesperson, Sabrina Singh. Russian sources said the missile’s range was 5,000 kilometres, meaning it would provide the capability to strike most of Europe and the west coast of the United States.
Tactical nuclear weapons exercise
Earlier in 2024, on 6 May 2024, the Russian Ministry of Defence announced an exercise to test preparation and use of tactical nuclear weapons, as a response to ‘certain provocative statements and threats made by some Western officials,’ referring to UK and French suggestions that the West should be more directly involved in the war in Ukraine. The exercise was held later in the month in a Russian district next to Ukraine. As Pavel Podvig notes, nuclear strike exercises are common among nuclear-armed states and are meant be part of the deterrence messaging, but few have ever been as explicitly linked to specific political or military developments as the one announced by Russia. ‘The Kremlin was clearly sending a message intended to convey its readiness to escalate,’ says Podvig, adding that the Kremlin appears to be following the signalling path charted by a number of hawkish Russian experts, and it cannot be ruled out that it is prepared to take more steps up the escalation ladder.
Quieting the nuclear rattle
Podvig believes it would be wrong to ignore Russia’s actions completely, if only to prevent it from moving to more provocative actions. ‘To prevent this from happening, the international community must double down on its message that nuclear threats are inadmissible. … Western states should tone down their own message of reliance on nuclear deterrence and work together with a broad coalition of states, from their allies to China and India and the states parties to the Treaty on the Prohibition of Nuclear Weapons. Opposition to nuclear use is a powerful unifying message that can bring together states that may have diverging views on the war in Ukraine. Such a coalition can render nuclear threats politically untenable, opening more options for supporting Ukraine’s efforts to defend itself’.
For more information, see the 2024 edition of the Nuclear Weapons Ban Monitor.
Each State Party undertakes never under any circumstances to ‘threaten to use nuclear weapons or other nuclear explosive devices’.
- Article (1)(1)(d) prohibits threatening to use a nuclear weapon or other nuclear explosive device at all times, and regardless of whether such 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.
- To violate the TPNW, a threat of use must be credible in the circumstances. This means that the threat must emanate from a person or an authority in a position to either direct or authorise the use of a nuclear explosive device. Typically, therefore, such a threat would be made by a senior (and pertinent) government official or leading member of the ruling party in a nuclear-armed state.
- The narrow wording in Article 1(1)(d) of the TPNW with the active verb ‘threaten to use’ requires that any signalled intention by a state to use nuclear weapons be specific as to the target of threatened use.
- Prohibited threats may, however, 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 thenorm in the TPNW should it do so.
- In certain circumstances of tension, a show of force by means of missile testing, an explosive test of a nuclear weapon, a military exercise involving possible use of nuclear weapons, or a nuclear strike exercise, could amount to unlawfully threatening to use nuclear weapons under the TPNW (along with other violations of the Treaty).
- Policies of nuclear ‘deterrence’ rest on willingness to use nuclear weapons. Accordingly, reflecting the severity of the danger, some experts take the view that a practice of nuclear ‘deterrence’ in and of itself constitutes an unlawful threat of use of nuclear weapons. It is the view of the Nuclear Weapons Ban Monitor that the broader concept of nuclear deterrence, where the threat to use nuclear weapons is general and not specific in nature, is not sufficient in itself to constitute threatening to use under the TPNW. Deterrence practices are, however, illegal under the prohibition on possession and stockpiling.
- The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) does not prohibit the threat of use of nuclear weapons.