With the expiration of the Strategic Arms Reduction Treaty (New START) on 5 February 2026, the world is entering a new and potentially extremely dangerous phase of nuclear policy. The latest and most significant agreement on nuclear arms control, in force between the United States and Russia since 2011, has reached the end of its legal life. The mechanisms that have helped manage strategic risks for decades are breaking down amid growing geopolitical tensions and intensifying competition between the great powers.
The history of nuclear arms control treaties dates to the agreements of the Cold War era. Beginning with the first strategic arms limitation treaties between the USSR and the US in the 1970s, this international security architecture reached its culmination in START III, signed in Prague in 2010. It limited the number of deployed strategic nuclear warheads on each side to 1,550, introduced mechanisms for regular inspections and data exchange, which made nuclear strategies more predictable and transparent.
Similar agreements have been terminated in previous years. For example, in 2002, the United States withdrew from the 1972 ABM Treaty (Anti-Ballistic Missile Treaty), and in 2019 from the 1987 INF Treaty (Intermediate-Range Nuclear Forces Treaty, covering missiles with a range of 500 to 5,500 km) . However, START III remained the last major restrictive framework agreement between Washington and Moscow, accounting for more than 90% of the world’s nuclear arsenals.
Since the signing of START III, the number of nuclear warheads has been significantly reduced, from approximately 70,000 in the 1980s to around 12,000 today, because of the consistent reduction of strategic arsenals.
However, the trend towards disarmament had come to a halt long before the official end of the treaty. Inspections were frozen during the COVID-19 pandemic and then finally disrupted after the escalation of the war in Ukraine, when Russia effectively suspended its participation in 2023. Although both sides continued to formally comply with quantitative restrictions, monitoring of compliance and data exchange virtually ceased.
The positions of Russia and the United States on the extension of the treaty differ significantly. The Russian leadership has emphasised that the expiry of the treaty does not mean a rejection of strategic stability and has even offered to voluntarily maintain quantitative restrictions for another year after 5 February 2026 to avoid destabilisation. This initiative was presented as a conciliatory step aimed at maintaining restraint.
However, Moscow’s proposal did not receive an official response from Washington. In recent years, the United States has made it clear that it sees no point in extending the old format and would prefer a new agreement, possibly with the participation of third parties, such as China, a country whose arsenal is growing rapidly, and which Washington considers a key element in future negotiations.
This approach is explained by the desire in American politics to go beyond bilateral restrictions and build a more comprehensive arms control architecture that considers today’s multipolar reality. However, without consensus from Russia and China, such intentions remain difficult to implement.
At the same time, the end of the treaty poses a serious challenge for the Pentagon, and the US military leadership has already discussed plans in case the control mechanism cannot be renewed. This reflects a deep understanding that a world without START III will be a world without clear, formal rules on nuclear deterrence.
Unlike the US and Russia, China has never been a party to the START treaty and has consistently refused to join bilateral strategic arms control formats. For decades, Beijing has argued that such agreements were originally designed for powers with comparable, significantly larger nuclear arsenals, while China’s capabilities have long remained many times smaller. In official Chinese rhetoric, participation in treaties such as the START was seen as an attempt to ‘preserve inequality’ and limit the PRC’s strategic deterrence capabilities.
However, the situation began to change in the 2020s. According to estimates by Western and independent think tanks, China has begun to rapidly build up its nuclear forces by constructing new silo launchers, expanding the maritime component of its nuclear triad, and improving its delivery systems.
Although Beijing continues to emphasise the defensive nature of its nuclear doctrine and its commitment to the principle of ‘no first use’ of nuclear weapons, the scale and pace of modernisation are causing concern among the United States and its allies. According to estimates by the US Department of Defence, China could increase its nuclear capacity to 1,500 warheads by 2035. As a result, strategic arms control is no longer a purely American-Russian issue and is increasingly becoming a multilateral challenge, where without China’s participation, any new agreements risk being incomplete and ineffective.
The European nuclear powers, the United Kingdom and France, were not parties to the START III treaty and were therefore not bound by its quantitative limitations or verification mechanisms. Nevertheless, London and Paris traditionally viewed START III as a key element of global strategic stability, as it restrained the arms race between the world’s two largest nuclear powers, the United States and Russia, and thus indirectly reduced the risks for Europe. The end of the treaty is perceived in European capitals not as a diplomatic issue, but as a direct factor in the growth of military and political threats on the continent.
Against this backdrop, both countries are consistently implementing programmes to modernise their own nuclear forces. In the early 2020s, the UK announced a review of previous restrictions on the number of nuclear warheads and an extension of the service life of its sea-based nuclear triad based on Dreadnought-class submarines. France, for its part, is investing in the renewal of both the sea-based and air-based components of its nuclear deterrent, emphasising the ‘sovereign’ nature of its nuclear doctrine.
The escalating tensions surrounding Ukraine, growing instability in the Middle East, and the effective dismantling of the arms control architecture are pushing London and Paris towards a more pragmatic and hard-line approach to security. Their approaches are increasingly moving away from the previous emphasis on diplomatic disarmament in favour of a concept of deterrence based on readiness for long-term confrontation and increased military capabilities. Thus, for the European nuclear powers, the end of START III symbolises the end of the era of treaty-based control and provides an additional argument in favour of strengthening their own nuclear capabilities as an instrument of political and military influence.
Other members of the so-called ‘nuclear club,’ India, Pakistan, Israel, and North Korea, are developing their nuclear arsenals outside the framework of START III and, in fact, outside the global strategic control system. Their nuclear policies are determined primarily by regional conflicts and asymmetric threats, rather than by the logic of global balance characteristic of US-Russian agreements. India and Pakistan, for example, continue to build up and modernise their nuclear forces against a backdrop of permanent tension over Kashmir. Both countries are investing in new delivery systems, including medium-range ballistic missiles and tactical nuclear weapons, which increases the risk of even a local conflict escalating to the nuclear level.
Israel, which does not officially acknowledge possessing nuclear weapons, adheres to a policy of strategic ambiguity, viewing its nuclear capability as a guarantee of survival in the unstable Middle East. The escalation of the situation around Iran and a series of regional crises only reinforce the importance of this tacit deterrent, which is completely outside the scope of international treaties.
North Korea, for its part, demonstratively uses nuclear weapons as a tool of political pressure and a guarantee of regime preservation. Regular missile tests, statements of readiness to use nuclear weapons pre-emptively, and refusal to engage in any negotiations on denuclearisation underscore that Pyongyang perceives its nuclear status as irreversible.
Taken together, the actions of these states show that the collapse of the treaty-based control system, symbolised by the end of START III, is increasing the fragmentation of the nuclear world. Nuclear weapons are increasingly seen not as a subject of global restrictions, but as a regional instrument of deterrence, pressure or survival, which makes the task of preventing proliferation and reducing nuclear risks much more difficult and less manageable.
The future of the strategic arms control system after the expiry of START III remains uncertain and allows for several scenarios. The most alarming of these is the scenario of an unregulated arms race. In the absence of legally binding restrictions and verification mechanisms, the major nuclear powers may resort to increasing the number of warheads and their delivery systems, guided by mutual distrust and the desire for strategic advantage. In such conditions, the risk of unintended escalation, misjudgements of the enemy’s intentions and crisis situations that could spiral out of control increases dramatically.
A less pessimistic scenario involves attempts to develop a new multilateral agreement. In theory, this would involve a transition from a bilateral US-Russian format to a broader control architecture involving China and, possibly, other nuclear powers. In practice, however, the implementation of such an approach faces serious obstacles: deep mutual distrust between key players, differences in the size and structure of nuclear arsenals, and a mismatch of strategic interests and political priorities.
Finally, there is an intermediate option – voluntary compliance with quantitative limits without a formal treaty. However, without transparent control mechanisms and mutual inspections, this format remains vulnerable and largely symbolic, unable to fully replace a comprehensive system of treaty-based control over strategic arms.
Appeals to reason by international leaders, from representatives of civil society to religious figures such as the Pope, calling for the extension of the treaty for the sake of peace, reflect a growing fear that the world may be on the brink of a new era of nuclear instability. How world leaders respond to this challenge will determine the future of international security: a world in which nuclear deterrence lives without rules, or a new international order based on responsible diplomacy and collective guarantees.