New START Expired: Will Russia & US Enter a New Nuclear Arms Race?

The expiration of the New Strategic Arms Reduction Treaty (START) on February 5, 2026, marks a significant turning point in international security, effectively ending decades of formal limitations on strategic nuclear weapons between the United States and Russia. While other treaties address space and the seabed, traditional arms control between the two superpowers has, for all intents and purposes, ceased. The question now is whether this will usher in a new arms race, or if a different path lies ahead.

Some analysts fear a renewed competition in nuclear arsenals, suggesting that without binding limits, the United States, Russia, and China will inevitably engage in a three-way buildup. This perspective views the situation as a complex “three-body problem,” where each actor reacts to the decisions of the others. However, others, like Heather Williams, posit that the end of New START does not necessarily foreshadow an arms race.

Here’s not entirely uncharted territory. Most professionals working on these issues have operated within a framework of bilateral arms control with Russia for decades. Predicting arms races is often more art than science, frequently conflating prediction with preference. Assessments depend on whether the problem is viewed through the lens of disarmament, deterrence, or the pursuit of nuclear primacy. For some, the treaty’s expiration is a tragedy, while for others, it presents new opportunities for the United States.

Despite concerns, a rapid escalation is not inevitable. Moscow is likely to proceed cautiously, focusing on maintaining its status as a nuclear peer to the United States and ensuring it has sufficient capacity to hedge against potential U.S. Breakthroughs in missile defense or counterforce capabilities. This is not a radical shift, but rather a continuation of existing strategies. The emergence of China as a formidable nuclear force further complicates the equation, introducing new strategic calculations.

According to a 2025 report, China possesses approximately 600 nuclear warheads, with more in production. The expansion of the number of nations with nuclear capabilities – from five in 1991 to at least nine today – adds another layer of complexity. This makes negotiating a successor agreement more challenging.

While the conventional wisdom suggests Russia has an initial advantage in nuclear modernization, the reality is more nuanced. Russia’s defense industrial constraints, economic challenges, and the costs of reconstituting its conventional forces after the Russo-Ukrainian War limit its capacity for a sustained arms race. Moscow continues to hold an advantage in non-strategic nuclear weapons and the diversity of its delivery systems, areas not covered by New START. This has spurred discussions in the United States about the need for greater force diversity to address this asymmetry.

Under Secretary of State for Arms Control Thomas DiNanno emphasized this point at a recent conference on disarmament in Geneva, noting that Russia had “modernized and expanded those nuclear forces,” creating an “intolerable disadvantage” for the United States, as most of its deployed nuclear weapons were subject to New START limits.

Despite Russia’s apparent advantages on paper, its ability to sustain a large-scale buildup is questionable. Russia’s current programs to replace existing intercontinental ballistic missiles are significantly behind schedule. New ballistic missile submarine production is slow, and production of new heavy bombers is nearly nonexistent. Novel nuclear weapon systems like the Poseidon, Avangard, and Burevestnik will be deployed in limited quantities and are unlikely to fundamentally alter the strategic balance.

Moscow’s constraints mean it will likely avoid an expensive quantitative arms race, focusing instead on maintaining parity with the United States through cheaper means, such as uploading more warheads onto existing missiles, and hedging against potential U.S. Technological advancements. This may explain why Russian President Vladimir Putin has repeatedly expressed appreciation for the treaty and offered to maintain New START’s quantitative limits.

Reports suggest talks are underway between Washington and Moscow regarding a potential agreement to continue observing the treaty limits for at least six months, though the reliability of these reports remains uncertain.

Given Russia’s limitations and differing force requirements, it is unclear why Moscow would actively seek an arms race. Russian Foreign Minister Sergei Lavrov recently reiterated Moscow’s offer to observe treaty limits, positioning Russia as interested in arms control even as it continues to modernize its nuclear forces. The United States, with its extended deterrence commitments to numerous allies, faces different strategic considerations than Russia, and its nuclear strategy is increasingly focused on China.

The current U.S. Position is that future arms control must include Russia and China, should not harm U.S. Interests or ignore noncompliance, and that Washington will negotiate from a “position of strength.”

The present situation is likely to mark the low point of deployed nuclear arsenals, as the world enters a new period of nuclear modernization, force expansion, and potential proliferation. Russia stands to gain little from these developments and will likely find itself reacting to them, seeking to maintain parity as cheaply as possible while hedging against threats to its arsenal’s survivability.

Bilateral arms control with Russia has been eroding since the early 2000s. The United States withdrew from the Anti-Ballistic Missile Treaty in 2002, and Russian violations led to the U.S. Withdrawal from the Intermediate-Range Nuclear Forces Treaty in 2019. New START was the last major arms control treaty between the two countries. The treaty required 18 on-site inspections per year, but these were suspended in March 2020 due to the COVID-19 pandemic and never resumed. Russia’s actions following its invasion of Ukraine further undermined the treaty, eventually leading the State Department to declare in January 2023 that Russia was not in compliance.

In February 2023, Putin announced Russia’s suspension of participation in New START. Russia has also been pursuing activities that could violate the Outer Space Treaty, such as developing a nuclear anti-satellite weapon.

As of 2025, Russia is estimated to have 1,718 strategic warheads deployed, with the capacity to potentially increase its deployed arsenal by up to 60 percent. However, Russia’s ability to rapidly expand its forces is constrained by its economic and industrial limitations. While Russia has invested heavily in nuclear modernization, its focus has been on replacing Soviet-era missiles with modernized variants, rather than significantly increasing the overall number of deployed systems.

Russia’s non-strategic nuclear weapons represent a significant advantage, and its production of these weapons has increased considerably in recent years. This area was not covered by New START, and it presents a unique challenge for arms control efforts.

the future of arms control will depend on a complex interplay of strategic calculations, economic realities, and political considerations. While the expiration of New START represents a setback, it does not necessarily mean that a new arms race is inevitable. Russia’s constraints and its interest in maintaining parity suggest that it will likely proceed cautiously, focusing on maintaining its nuclear capabilities without engaging in a costly and destabilizing buildup.