Experts from leading international institutions in the field of disarmament told RBC how the expiration of the START Treaty will affect international security and what steps Russia and the United States can take right now.
On February 5, 2026, the Russian-American Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (START III), the last existing agreement regulating the nuclear arsenals of Russia and the United States, ended.
Alexey Arbatov, Head of the IMEMO RAS Center for International Security, Academician of the Russian Academy of Sciences
The main threat to the expiration of the START Treaty is that it will be much more difficult to resume negotiations to conclude the next agreement. There is no transparency and predictability associated with control mechanisms now, and we will gradually lose sight of each other's strengths. Usually, previous agreements were the starting points on which new agreements were based. So these reference points will become a thing of the past. Under the previous agreement, there was a clear understanding of the degree of sustainability of strategic stability - it was supported by models, the most accurate calculations, and technical assessments. In the absence of a contract, this view will be blurred. We will find ourselves in a situation of great uncertainty, and such a situation is always dangerous. This situation developed in 1962, when the Caribbean missile crisis occurred, which almost brought us to a nuclear war. We can approach this situation again, especially since now there will be not two players, but much more.
After the expiration of the agreement, the deployment of additional warheads on carriers will be the cheapest way. If the United States initiates it, Russia, of course, will do the same. We don't have the same capabilities in terms of placing warheads: if we talk about returning warheads from storage to missiles and loading aircraft with cruise missiles, the United States has an advantage here. This will not lead to a nuclear war, but it will shift the starting points in the strategic balance. It will take years to implement new systems, but over the years we may lose track of what the balance is and how to regulate it.
Now, in addition to starting consultations on the possibility of resuming negotiations on strategic stability, we need to prepare for the next Review Conference on the NPT (this conference of the Treaty on the Non-Proliferation of Nuclear Weapons takes place every five years. - RBC). And it is very important for us to find common ground with the Americans, so that together with the three other nuclear powers (Great Britain, China, France. - RBC) to adopt a joint statement by which we would confirm our commitment to reducing nuclear weapons, and moratoriums on explosive nuclear tests, and the non-deployment of nuclear weapons in outer space, as well as many other activities in this area. There are many initiatives that can be promoted to prevent the upcoming conference from failing. The previous two failed because they could not adopt the final document. If this fails, the nuclear weapons control regime will begin to disintegrate, which is no less dangerous than the loss of channels for negotiations on strategic stability.
Pavel Podvig, Senior Researcher at the United Nations Institute for Disarmament Research (Geneva)
Of course, the expiration of the contract will not help to improve the security situation. At the same time, you need to understand that there will still be no immediate deterioration. The deterioration that could have happened has already happened in many ways, and the expiration of the contract is its symptom, not its result.
It is important to take into account that the capabilities of all parties (including, probably, China) to significantly increase their nuclear forces are quite limited. What can be done relatively quickly is the return to the carriers of warheads that were once stored in reserve. The United States will be able to roughly double the number of deployed warheads within about a year or two, while Russia will be able to increase this number by about one and a half times. But it is unlikely that such an increase will be made quickly or fully.
It can be expected that after the expiration of the treaty, the United States will declare that there are no restrictions now. But they are unlikely to announce specific plans to increase the size of the arsenal. In September, Russia put forward a proposal to comply with the treaty's ceilings for at least a year. Most likely, this intention will be confirmed regardless of what the United States does. In principle, it cannot be ruled out that the initiative will be extended further. But a lot depends on how the political situation and relations between the United States and Russia will change.
As for specific measures now, the United States could declare that it accepts the Russian initiative and is ready to comply with the quantitative restrictions of the treaty. At first, for a year, but in a year it will be more difficult to abandon such obligations than it is today, so it can last further. The probability of such a move on the part of the United States is extremely low, mainly because the United States has the opinion that they need to increase their arsenal in order to confront Russia and China at once. In addition, the United States points out that it is impossible to verify compliance with obligations. This is fair enough, but ideally, the United States and Russia could resume data exchange. Such a step is quite realistic and, strictly speaking, does not require a contract (unlike, for example, inspections). In principle, resuming data exchange would be a good step, even if the parties build up their arsenals.
Tyutti Eraste, Senior Researcher at the Weapons of Mass Destruction (WMD) Program at the Stockholm International Peace Research Institute (SIPRI)
In addition to excluding the vast Russian and American nuclear arsenals from the contractual restrictions on deployed nuclear warheads, the expiration of the START treaty means a loss of transparency and channels that have helped build trust between the two countries. In the long term, this could increase mutual distrust and an arms race, which would strengthen the positions of hardliners in both countries and possibly lead to a further build-up of nuclear capabilities.
Now Russia and the United States should formalize an agreement on compliance with the START Treaty restrictions, as proposed by Vladimir Putin in September 2025. They should also seek to resume bilateral arms control within the framework of a new treaty that would cover both nuclear weapons and non-nuclear strategic systems, in particular missile defense systems. However, it is difficult to imagine this in practice, since they have not been able to agree on this issue for the past 25 years.
Thus, a more likely scenario is the continuation of the impasse in the field of arms control, which implies the need for additional efforts to reduce risks and build confidence outside the framework of conventional treaties.
Nikolai Sokov, Senior Researcher at the Vienna Center for Disarmament and Non-Proliferation (VCDNP)
The contract has only a symbolic meaning. Its main purpose is to ensure transparency of strategic arsenals, and it has long been lost. Quantitative and qualitative restrictions were to become the subject of a large agreement, negotiations on which had not even begun. Moreover, Russia is developing weapons that are not covered by the treaty ( Burevestnik and Poseidon ), and the United States is considering a significant build-up of strategic weapons in response to the growth of the Chinese arsenal - none of this will prevent the START Treaty.
But symbolism is also important - for the first time since 1969, the United States and Russia will not only live in the absence of a treaty (this has happened before), but even in the absence of negotiations. And this is serious. We can expect a serious scandal at the NPT Review Conference, and, as it seems to me, this is the main argument in favor of accepting the Russian proposal on informal compliance with the limits.
Negotiations on a new document should begin as soon as possible, ideally before the NPT Conference. The problem is that Donald Trump shows no interest in this, and the US government has serious opposition to the very idea of arms control. At the same time, negotiations, if they begin, will be difficult and will take a long time, and a new agreement will have to wait a long time.
Here, a more urgent task arises - measures to reduce risks. Those that are in effect now (for example, advance notifications to Russia and the United States about strategic missile launches) are good, but very few; since the start of the START Treaty, new weapons have appeared, both conventional and dual-use, so measures need to be expanded and qualitatively deepened. There are prospects for this - after all, it is possible to agree on risk reduction measures much faster than on arms control.
The main problem for the near future is the uncertainty and unpredictability of the strategic balance and, more broadly, the security situation. Risk mitigation measures will help to stabilize the situation, and hopefully a new agreement will arrive.
Steven Pifer is an affiliated employee of the Center for International Security and Cooperation at Stanford University (Center for International Security and Cooperation - CISAC)
The expiration of the START III treaty will have negative consequences for international security. For the first time in almost four decades, there will be no restrictions on the nuclear forces of the United States and Russia. There will also be no verification and transparency measures allowing the United States and Russia to track the other side's forces. This comes at a time when both Washington and Moscow seem to be considering increasing their strategic nuclear forces. Of course, there is also the problem of China, which is building up its nuclear arsenal faster than any other country.
Unfortunately, it seems that China, Russia and the United States do not show much interest in actions to mitigate or prevent a nuclear arms race. Beijing categorically refuses to discuss nuclear arms control. Moscow refuses to discuss issues of strategic stability or what might happen after START III until Washington takes a more positive stance towards Russia. And the Trump administration doesn't seem to have much interest in arms control either.
Thus, I fear that we are heading towards a nuclear arms race. Let's hope that things don't go too far before wiser people remember the lesson learned by Washington and Moscow in the 1960s: if you increase the number of nuclear weapons and the other side does the same, you will most likely not increase your security, but increase costs and nuclear risks.
Member of the Council of the Pugwash Movement of Scientists, Ambassador Extraordinary and Plenipotentiary, retired Sergey Batsanov
In a political sense, the end of the START Treaty gives a green light to an unlimited nuclear arms race, whets the appetites of the largest military contractors and helps eliminate the very concept of limiting nuclear weapons from the political lexicon. This applies not only to Russia and the United States, but also to other recognized or unrecognized smaller nuclear powers, as well as to a number of so-called non-nuclear countries, whose ruling elites are increasingly thinking about acquiring their own or collective nuclear arsenals.
At the same time, it would not be entirely correct to say that all these risks are the result of the termination of the START Treaty. Much depends on the nature of political processes in the world, the current strategic priorities of the leading powers, and the positions of other countries, as well as the public.
The implementation of Vladimir Putin's initiative, which he put forward in September 2025, would be the first step towards reducing risks. The next step could be a similar statement by the US president. It would also be extremely important for the concept of strategic restraint to be supported by other countries and relevant non-governmental organizations (NGOs).
It is important to keep in mind that the next NPT Review Conference will open in New York in less than three months. The Treaty is not in the best shape right now; there are many reasons for this, but one of the key ones is the ongoing scrapping of the international nuclear arms limitation system. Therefore, it would be worthwhile right now to think about how the conference could support the idea of maintaining restraint in the field of strategic offensive arms, and adopt a short but succinct final document reflecting this idea.
Naturally, the question arises where and how to move forward in matters of limitation and non-proliferation of nuclear weapons. Currently, various media and other public spheres are actively filled with fatalistic and even optimistic comments about the inevitability of a nuclear arms race and nuclear proliferation. This is dangerous, including from the point of view of Russia's interests. Therefore, if the Russian initiative to maintain the central restrictions of the START Treaty gets a positive development, and the world gets some kind of respite, this should be used to develop new approaches to limiting nuclear weapons both through Russia and the United States, and with the involvement of other nuclear powers, not only China, but also, to no lesser extent, England and France. It will not be possible to start such negotiations tomorrow, but it would be worthwhile to start relevant discussions at the conceptual level.
Ekaterina Postnikova
