Atomized

For the first time since the end of the Cold War, the use of a nuclear weapon in Europe is a plausible scenario. Since launching its full-scale invasion of Ukraine on February 24, 2022, Russia has issued numerous thinly veiled nuclear threats against its neighbor.^[1] That it would actually carry out such a threat seems unlikely, but this possibility cannot be ruled out.^[2] In its war against Ukraine, Russia has not only used reckless rhetoric, but reckless actions as well: its shelling of nuclear plants and abudctions of personnel have put both the safe operation of the Zaporizhzhia nuclear plant, the largest in Europe, as well as the safe storage of radioactive materials at the former nuclear power plant Chernobyl at risk.^[3]

With its revisionist war of aggression, Russia has upended the international nuclear order. By threatening the use of nuclear weapons against Ukraine, a state that in 1994 gave up its own nuclear arsenal in exchange for Russia’s commitment to respect Ukrainian sovereignty and territorial integrity,^[4] Russia has undermined two key pillars of this order: the 1968 Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and the nuclear taboo. The NPT, at its core, is a grand bargain in which the five recognized nuclear-weapon states – China, France, Russia, the United Kingdom, and the United States – pledged to act as responsible nuclear powers and pursue eventual nuclear disarmament in exchange for the continued non-proliferation of the other NPT parties.^[5] The nuclear taboo refers to the idea that nuclear weapons are weapons of mass destruction so abhorrent that their use is considered unacceptable.^[6] By questioning the nuclear taboo, neglecting its obligations under the NPT, and breaking its commitment to Ukraine, Russia has lost its credibility as a responsible nuclear-weapon state.

Russia’s nuclear threats pose a fundamental challenge to those seeking to prevent the use of nuclear weapons now and in the future. If a Russian nuclear strike against Ukraine were to go unpunished, it would severely damage the existing nuclear order and make future use of nuclear weapons more likely, as it would set a precedent of nuclear attacks being an acceptable and possibly beneficial course of action in military conflict.^[7] There is also
a risk, however, of triggering a spiral of further escalation with a strong response to a Russian nuclear attack. Therefore, the international community’s response to such an attack would have to be measured enough to prevent further escalation, yet strong enough to prevent the precedent of an unpunished nuclear strike.^[8]

Alas, Russian brinkmanship is only the most immediate threat to the international nuclear order. A wide range of other threats and challenges stem from other revisionist actors. In an environment of rising geopolitical tensions and eroding arms control regimes, such challenges have the potential to fundamentally change the global nuclear security architecture.

The international nuclear arms control regime has been eroding for some time. Since the 2002 US withdrawal from the US–Russian Anti-Ballistic Missile Treaty, North Korea has left the NPT, Russia violated the Intermediate-Range Nuclear Forces Treaty – prompting the US to withdraw from it –, the US pulled out of the Joint Comprehensive Plan of Action, also known as the Iran nuclear deal, and the US and Russia left the Open Skies Treaty.^[9] New START, the last existing bilateral nuclear arms control treaty between the US and Russia, is set to expire in 2026, and its replacement by a new treaty is uncertain.^[10] Although US President Joseph Biden recently expressed his willingness to negotiate one, he also indicated it is Russia’s responsibility to demonstrate its commitment to resuming arms control cooperation after its invasion of Ukraine.^[11] Whether Russia will take this initiative is uncertain. With ever fewer nuclear arms control treaties in place, the world is approaching the wrong kind of “global zero” – a world with zero arms control treaties but an increasing number of nuclear warheads.

The five nuclear-armed permanent UN Security Council members caused a flicker of optimism when they issued a statement in January 2022 stating that nuclear war “cannot be won and must never be fought,” thereby seemingly reaffirming their commitment to the nuclear taboo.^[12] This optimism waned, however, as Russia launched its invasion of Ukraine and started issuing nuclear threats. In August, the NPT Review Conference, which was held by the parties to the NPT to review the treaty’s implementation, failed to adopt a substantive outcome document due to Russian objections over a reference to the safety of the Zaporizhzhia nuclear power plant. This failure dealt yet more damage to the nuclear order and further isolated Russia on the international stage.^[13] The lack of cooperation between the nuclear-weapon states party to the NPT, a key pillar of the international nuclear order, undermines the sustainability of this order.^[14]

With its withdrawal from the Iran nuclear deal, the US has not only violated a UN Security Council resolution,^[15] thereby dealing a further blow to the UN’s authority, but also greatly reduced Iran’s nuclear breakout time.^[16] Although negotiations to revive the agreement started in 2021, revival efforts are complicated by domestic opposition to the agreement in both Iran and the US, Iran’s recent deliveries of weaponry to Russia for use against Ukraine, and Iran’s brutal repression of domestic protests.^[17] If Iran were to produce nuclear warheads, this could trigger a nuclear arms race in the Middle East. Proliferation cascades have been wrongly predicted before, and other would-be Middle Eastern nuclear powers would face obstacles on their way to the bomb, but Saudi Arabia would feel pressured to seek nuclear weapons in such a scenario. Meanwhile, Iranian proliferation might cause Israel – already a nuclear power – to consider a preemptive strike against Iran, given the long history of Iranian threats to annihilate the country and its people.^[18]

These new developments that further hollow out the nuclear arms control regime come on top of already existing challenges to this regime. Already, four states outside of the NPT framework possess nuclear weapons. Three of these, India, Israel, and Pakistan, never signed the NPT.^[19] The fourth, North Korea, withdrew from the NPT in 2003, although it is disputed whether this withdrawal is valid under international law.^[20] Political developments in some of these states also pose risks to international nuclear security. Enduring political instability in Pakistan raises questions on how responsibly the country will be able to handle its nuclear arsenal in the future.^[21] North Korea, meanwhile, conducted 86 missile tests in 2022 alone, a record number for the country.^[22] There are also indications that it is preparing for a new nuclear test. In September, North Korean leader Kim Jong-un announced a more assertive nuclear posture, which allows for nuclear first-use under certain circumstances.^[23]

These “extra-NPT” nuclear activities are examples of a revisionist challenge by the non-NPT nuclear-weapon states and Iran vis-à-vis the NPT-based nuclear order, which seeks to classify them as non-nuclear-weapon states. With its aggressive behavior, North Korea takes this challenge even further than the other states, thereby threatening the security of states in East Asia and beyond.

Meanwhile, the circumstances for reinvigorating nuclear arms control regimes are suboptimal: great-power competition is becoming ever more intense, trust among nuclear and would-be nuclear adversaries is low, and few are willing to risk losing geopolitical competitive advantages by pursuing arms control measures. Nonetheless, the international community must recommit to arms control. The further erosion of the international nuclear arms control regime has removed important safeguards against further nuclear proliferation, arms races between existing nuclear powers, unintended nuclear escalations, and all the risks that come with those. But the Cold War has shown that even in times of great-power competition, arms control cooperation may be possible.

A new nuclear arms race may already be underway: there are strong signs that China is on track to massively expand its nuclear arsenal in the coming decade.^[24] Compared to Russia and the US, with 4,477 and 3,708 nuclear warheads, respectively, China maintains a modest arsenal of 350 warheads.^[25] This arsenal has, however, grown steadily in recent years and might grow even faster in the coming decade (Figure 6.1).^[26] In 2021, the US Department of Defense estimated that China might possess as many as 1,000 warheads by 2030,^[27] given that China is currently constructing approximately 280 new nuclear missile silos, more than ten times as many as it operates today (Figure 6.2).^[28]

China’s nuclear expansion also constitutes a revisionist challenge to the nuclear order in which the US and Russia are the two nuclear superpowers. By expanding its nuclear arsenal without being transparent about it and refusing to engage in arms control talks, China seeks to either join the ranks as a nuclear superpower, or at least strengthen its strategic position relative to Russia and the US. This expansion could, for example, provide China with additional leverage in a confrontation with the US over Taiwan.^[32]

Ever since former US President Donald Trump sowed doubt about the US’s commitment to defending its allies, the credibility of US extended nuclear deterrence has become the subject of debate.^[33] Trump may no longer be president, but a return to the White House of someone without a strong commitment to the US’s alliances remains a possibility. Furthermore, the possibility that the US nuclear arsenal may soon have to deter two nuclear peer-competitors raises questions regarding the long-term ability of the US to live up to its extended nuclear deterrence commitments.^[34] Some experts have warned that a further loss of credibility in this area could trigger a new form of nuclear revisionism: if US allies no longer trust in the US security guarantees that they received in exchange for their commitment to non-proliferation, some of them may seek to become nuclear-weapon states themselves.^[35]

US allies in Asia, for example, face both an expanding Chinese nuclear arsenal and continuing nuclear threats by North Korea. In South Korea, popular support for the acquisition of a national nuclear arsenal is increasing, with one 2022 poll putting it as high as 71 percent.^[36] In Japan, on the contrary, several polls in recent years showed broad popular support for joining the Treaty on the Prohibition of Nuclear Weapons (TPNW).^[37] At the same time, Japan’s 2022 national security strategy, although not announcing nuclear proliferation in any way, does seem to signal a pivot to much more assertive foreign policy and security policy in response to the increasing threats posed by China and North Korea.^[38] This, together with the fact that Japan is a nuclear-threshold state, meaning it possesses the technological capabilities to develop nuclear weapons if it decided to do so, would make Japan a potential proliferation risk if it were to ever lose faith in the US-provided nuclear umbrella.^[39]

The TPNW, which has 68 state parties and 91 signatory states, poses a different kind of revisionist challenge to the existing nuclear order.^[40] As frustration over the lack of progress on arms control by NPT nuclear-weapon states grew, several civil society organizations initiated a campaign for a treaty banning nuclear weapons altogether.^[41] In 2017, this led several non-nuclear-weapon NPT states to launch the TPNW in an effort to promote the implementation of NPT Article VI, which outlines the obligation of nuclear-weapon states to work toward complete nuclear disarmament.^[42] The TPNW thus seeks to change the nuclear order by eliminating all nuclear weapon arsenals, including those of the states permitted to have them under the NPT. It mainly draws support from smaller states from the “Global South” that neither have nuclear weapons nor enjoy the benefits of a nuclear umbrella (Figures 6.3 and 6.4).^[43]

Faced with deteriorating geopolitical conditions, the TPNW has been unable to make significant inroads among states who enjoy the benefits of nuclear deterrence, either through their own nuclear arsenal or an ally’s extended nuclear deterrence. In its 2022 Strategic Concept, the North Atlantic Treaty Organization (NATO) reaffirmed it will remain a nuclear alliance as long as nuclear weapons exist.^[44] The US also reiterated its rejection of the TPNW in its 2022 Nuclear Posture Review.^[45] And in Europe, Russia’s attack on Ukraine has decreased enthusiasm for the TPNW. A 2022 public opinion poll showed that support for nuclear deterrence has significantly increased in Germany, a country traditionally very skeptical of it. Now, a plurality of 38 percent of the population supports Germany’s participation in NATO’s nuclear sharing arrangement, whereas 31 percent reject it.^[46] The 2022 decision to buy dual-capable F-35 aircraft signaled that the German government remains committed to NATO’s nuclear-sharing arrangement.^[47] Finland’s and Sweden’s applications to join NATO have probably ended any hopes of these states, both TPNW observers, actually joining the treaty.^[48] These issues add to the already existing problems for the TPNW, such as criticism of its proposed non-proliferation verification mechanisms and the fact that its strategy of relying on societal pressure to motivate nuclear-weapon states to join is ineffective in autocracies and thus selectively targets democracies.^[49]

Although the TPNW may face difficulties convincing more states to join, its broad support in the “Global South” is a signal to be taken seriously. It shows the widespread frustration among non-nuclear-weapon states in this part of the world with the lack of progress on implementing Article VI of the NPT and with the inequality of the nuclear order. If this discontent is not addressed, the NPT risks losing credibility.

The existing nuclear order faces various challenges: nuclear brinkmanship by Russia and North Korea, nuclear expansion by China, and various horizontal proliferation risks. The safeguards provided by arms control treaties are steadily eroding. Meanwhile, an alternative and more radical arms control regime in the form of the TPNW challenges the existing regime built around the NPT.

The nuclear order needs revision to again enjoy the broad support among the international community that is needed to ensure nuclear stability and arms control. With great-power competition on the rise, this is difficult. Nevertheless, world leaders must make an effort, wherever possible, to reestablish a nuclear order that halts further proliferation and promotes arms control. This requires cooperation on these issues between the NPT nuclear-weapon states. It is especially critical here to build an incentive structure to convince China to create transparency regarding its nuclear arsenal expansion and engage in arms control discussions. If substantial reductions of nuclear arsenals are to prove unobtainable in the current geopolitical environment, nuclear powers should at least try and expand transparency and nuclear risk-reduction measures. Such measures could include a satellite non-interference treaty, ensuring parties’ capabilities to observe each other’s nuclear capabilities, as well as more active use of the Washington–Beijing military hotline.^[50] Reinvigorating arms control regimes may be difficult, but nuclear powers must nonetheless try. The likely alternative is unregulated arms races and further nuclear proliferation, with all the associated risks.