A new nuclear world: an unlimited arms race

As of 5 February 2026, the US-Russian New START Treaty, the last international agreement on nuclear arms control, will expire. Prior to this, Moscow and Washington have already been highly successful in dismantling the once multifaceted and multi-layered system of nuclear arms control that existed for more than half a century. One need only recall the termination of the Intermediate-Range Nuclear Forces (INF) Treaty. As a result, no agreements will remain to limit the dangerous build-up of nuclear weapons in the context of an increasingly confrontational global environment. 

The New START Treaty limited the nuclear arsenals of Russia and the United States to 1,550 warheads, 700 deployed intercontinental ballistic missiles, submarine-launched ballistic missiles, and heavy bombers equipped with nuclear weapons on each side. Verification measures, data exchange, and confidence-building mechanisms were also key elements of the treaty. In particular, it included a system of short-notice on-site inspections, allowing each side to verify the other’s compliance. This enabled Moscow and Washington to draw conclusions about each other’s nuclear strategy, strategic force development, and intentions. However, these transparency measures were abandoned when Putin suspended the treaty in February 2023, citing US aid to Ukraine as the reason. Now that the New START Treaty has expired, quantitative restrictions on the growth of both countries’ nuclear arsenals are also disappearing.

It is unlikely that a nuclear arms race will begin immediately. Both Moscow and Washington are currently implementing long-term and extremely costly programmes to modernise their nuclear arsenals. These programmes focus primarily on replacing missiles that have reached the end of their service life. It will take years before either side is able to exceed the New START limits by deploying new missiles. However, it cannot be ruled out that, taking advantage of the treaty’s termination, the United States will proceed with what is known as an “upload”, returning reserve warheads to existing missiles. US upload potential would allow the number of deployed warheads to increase from the New START limit of 1,550 to around 3,500. Apparently fearing such a development, Putin proposed in September 2025 that the treaty’s core quantitative restrictions should continue to be observed for one year after 5 February 2026. This proposal was not supported by the American president, who said in a January 2026 interview: “If it expires, it expires. We’ll do a better agreement.” He was clearly hinting at his repeatedly stated proposal to negotiate a similar agreement with China’s participation. However, Beijing’s current position renders this proposal entirely unrealistic.

It also cannot be ruled out that Moscow will deploy, or at least announce the deployment of, new “exotic” types of nuclear weapons that could be considered strategic, such as the Burevestnik nuclear-powered cruise missile and the Poseidon underwater drone. This is just one example of the dangerous strategic uncertainty that may arise. The elimination of the New START Treaty will force each side to rely solely on its own intelligence assessments of the other’s actions. With insufficient knowledge of the opposing side’s intentions, military planners will assume worst-case scenarios, greatly increasing the risk not only of an uncontrolled nuclear arms race but also of direct nuclear confrontation. During the war against Ukraine, the Kremlin repeatedly threatened to use nuclear weapons. In effect, Moscow and Washington now find themselves in a situation comparable to that on the eve of the Cuban Missile Crisis.

A new arms race could also push the parties to abandon the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and resume nuclear testing. Putin has hinted at such a possibility. In addition, a new threat to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is emerging. It is no secret that, in the context of unprovoked aggression against Ukraine, a number of countries are now considering the need to possess nuclear weapons. The NPT includes a commitment by nuclear-weapon states to pursue the reduction and eventual elimination of these weapons. That commitment is now no longer supported by concrete measures, making it easier for non-nuclear states to withdraw from the treaty.

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