How North Korea’s Entry into the Russo-Ukrainian War Further Undermines the International Nuclear Order

Executive summary

Russia’s expansionist and genocidal war against Ukraine is shattering the rules and norms of the international security order in a number of ways. The war poses particular challenges to the nuclear non-proliferation regime, insofar as Russia is a nuclear-weapon state as defined in the Nuclear Non-Proliferation Treaty (NPT) and is trying to conquer as well as destroy Ukraine, a non-nuclear-weapon state in full compliance with its NPT obligations. Specifically, Russia is engaged in nuclear blackmail against Ukraine and its partners, including other non-nuclear-weapon states that are parties to the NPT, which undermines the Treaty. Having earlier supported Russia’s war with large deliveries of military equipment and ammunition, Pyongyang is now a full party to Moscow’s attack on Ukraine. Russia, in the meantime, has begun shielding nuclear-armed North Korea against international denuclearization efforts.

Ukraine agreed in 1994 to give up the atomic weapons it had inherited from the Soviet Union and to join the NPT as a non-nuclear-weapon state, in exchange for which it received security assurances from the NPT’s five nuclear-weapon states. However, it is now fighting a war against two nuclear-weapon possessor states, including one, North Korea, that earlier violated the NPT, and another, Russia, that gave Kyiv guarantees that it would never threaten Ukraine's territorial integrity if Ukraine renounced nuclear weapons. All NPT signatory states concerned about the preservation of the non-proliferation regime should provide Ukraine with as much military and non-military help as possible to restore its territorial integrity, preserve its national sovereignty and achieve a just peace.

Introduction

The nuclear dimension has been a key aspect of the Russo-Ukrainian War since it began in February 2014. Behaviour in this war, not just by Moscow and Kyiv, but also by other states, has been conditioned by Russia’s possession and Ukraine’s non-possession of weapons of mass destruction. Russia has the world’s largest arsenal of atomic warheads.

Moscow has been eager to repeatedly remind the world of its destructive nuclear power since 2014. In November 2024, the Kremlin publicly amended the Russian Federation’s military doctrine to make Moscow’s nuclear threats more credible by lowering its threshold for the use of nuclear weapons. In contrast, Kyiv agreed in 1994 to give up its inherited Soviet-era atomic warheads, and thus today has no nuclear deterrence capability.

Oddly, this situation is legitimized, supported and protected by international law. On the one side, the Nuclear Non-Proliferation Treaty (NPT) allows Russia, as an official nuclear-weapon state, to possess nuclear weapons. On the other side, the NPT explicitly forbids Ukraine, as an official non-nuclear weapon state, to do the same. Ukraine’s non-nuclear allies are similarly bound by the NPT to their status as conventional military powers in supporting Ukraine.

Having earlier defied international law and the Helsinki Final Act through its territorial expansions into Moldova, Georgia and Ukraine, Moscow is undermining the logic of the non-proliferation regime and the letter of the NPT with its nuclear posturing. In its preamble, the NPT prescribes that “States must refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State”. In particular, such use or threat of use of force by a nuclear-weapon state against a non-nuclear-weapon state is inadmissible.

Effects of North Korea’s Participation in the Russo-Ukrainian War

The logic of nuclear non-proliferation is now also under attack through North Korea’s entry into the Russo-Ukrainian War. Since 2023, Russia has been increasingly relying upon North Korea, a state that earlier violated the NPT, in the conduct of its assault on Ukraine. Having already supported Russia’s war heavily through the supply of military equipment and ammunition, Pyongyang extended its collaboration with Moscow in the autumn of 2024 by sending regular troops to fight against Ukraine. These North Korean military units have already engaged in direct combat against Ukrainian forces and taken significant casualties. North Korea’s engagement in this conflict is helping to expand the scope and scale of the war into a global conflagration.

To be sure, North Korea withdrew from the NPT in 2003, long before its involvement in a European war. On its official departure from the Treaty more than 20 years ago, Pyongyang stated that it would no longer be bound by the NPT’s rules. It has since felt free to construct and test nuclear weapons and their associated delivery systems without restriction. (In fact, it had been violating the NPT while still a state party, flouting the international consequences, which included UN and other sanctions.) North Korea is now one of the world’s four nuclear-weapon possessor states outside the NPT along with India, Pakistan and Israel.

Nonetheless, North Korea’s change of status in the international nuclear order in 2003 does not reduce the importance of the effects on the non-proliferation regime of its participation, in the form of weapon deliveries and sending thousands of troops, in Russia’s armed attack on Ukraine. Neither Moscow’s initiation of military hostilities in 2014, nor Pyongyang’s full entry into the war ten years later have diminished the NPT’s absolute restriction on Ukraine’s ability to seek the benefits of nuclear deterrence and defence. Dutiful observance of the NPT is now putting Ukraine at a disadvantage vis-à-vis two nuclear-weapon possessor states – Russia as an official nuclear-weapon state, and North Korea as a de facto nuclear-weapon state outside the NPT.

This novel situation puts the geopolitical role of the NPT under even more pressure than was the case during the bilateral phase of the Russo-Ukrainian War from 2014 to 2023. Treaty implementation by Ukraine and its non-nuclear allies looks now doubly disadvantageous as it puts them at risk vis-à-vis Russia, one of the Treaty’s official nuclear-weapon states, and restricts their room for manoeuvre in relation to the war being waged against Ukraine by North Korea. Ukraine is being attacked by nuclear-weapon possessor states with two different legal statuses with no recourse in the context of the NPT to address this unprecedented situation.

North Korea’s violation of and absence from the non-proliferation regime has been giving it freedom of international action. The Russian-North Korean alliance further undermines the NPT by demonstrating that nuclearization need not have consequences and can even result in more security benefits. This lesson is surely being studied closely in, among other capitals, Seoul, Taipei and Tokyo. In contrast, observance of the NPT by Ukraine circumscribes its ability to seek tit-for-tat means of defending itself against Russia and North Korea, within the right of states to defend themselves defined under article 51 of the United Nations Charter.

North Korea’s new relationship with Russia in connection with the Russo-Ukrainian War also touches on other Russian obligations under the NPT. In June 2024, Vladimir Putin and Kim Jong Un signed a Comprehensive Strategic Partnership Treaty, which entered into force in early December 2024. It includes a promise to defend each other in case of armed attack that could, presumably, involve Russia or North Korea using nuclear weapons. In addition, both sides commit to opposing “the application of unilateral compulsory measures including the measures that assume extraterritorial nature.” 

The Institute for the Study of War has described the new situation that has emerged in the following way: “[…] Russia has abandoned its past opposition to North Korea’s nuclear program. It vetoed a UN Resolution to tighten sanctions on North Korea in 2022 and another UN Resolution to extend the mandate of the UN sanctions monitoring committee on North Korea in 2024, effectively ending UN sanctions compliance monitoring”.

Although still officially a nuclear-weapon state, Russia no longer upholds the sanctions on North Korea that, as one of the five permanent members of the UN Security Council, it introduced in response to, among other things, North Korea’s development of nuclear weapons outside the NPT. Instead, Moscow has accepted and legitimized Pyongyang’s right to possess nuclear weapons. Russia’s Foreign Minister, Sergei Lavrov, stated in September 2024 that “applying the term ‘denuclearisation’ to [the] DPRK [Democratic People’s Republic of Korea] no longer makes any sense. For us, this is off the table.”

Conclusions

The nuclear non-proliferation regime came into being with the entry-into-force of the NPT in 1970. It has since drawn its legitimacy from being an all-encompassing agreement that helps to prevent nuclear war and proliferation, while also preventing the use or threat of use of nuclear weapons by nuclear-weapon states against non-nuclear-weapon states in good standing with their NPT obligations. Today, however, it is inadvertently generating rather different effects by providing cover for Russia, as an NPT-defined nuclear-weapon state and permanent member of the UN Security Council, to carry out expansionist policies against an official non-nuclear-weapon state in violation of explicit pledges made in 1994 not to do so.

Moreover, this state – Ukraine – once possessed a large arsenal of atomic warheads but voluntarily abandoned them and related infrastructure in order to join the NPT as a non-nuclear-weapon state. In return, Russia, the US and UK pledged, in the 1994 Budapest Memorandum, that they will “respect the independence and sovereignty and the existing borders of Ukraine,” as well as “refrain from the threat or use of force against the territorial integrity or political independence of Ukraine, and that none of their weapons will ever be used against Ukraine […].” Against this background, there must be some consequence within the NPT for any nuclear-weapon state that takes the actions that Russia is doing today. Punitive measures could include anything from removing access to the benefits of the peaceful use of nuclear technology, e. g. by cutting Russia off from nuclear power markets, to removing voting rights in various NPT forums.

Today, the corrosive effects of Russia’s expansion into Ukraine on the global security order are being further aggravated by the increased involvement of North Korea, a nuclear-weapon possessor state outside the NPT, in the Russo-Ukrainian War. In order to preserve the non-proliferation regime, all signatory states to the NPT should be unequivocal in their support for Ukraine. They should provide military or non-military help to enable Kyiv to achieve a convincing victory on the battlefield, leading to a liberation of all Ukrainian territories currently illegally occupied by Russia. Upholding the logic of nuclear non-proliferation demands a just peace that does not allow Russia to harvest any fruits from its aggression, upholds respect for international law, including its central principles of national sovereignty and territorial integrity, and compensates Ukraine for its losses.

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