On February 5, 2026, the last legally binding nuclear arms control agreement between the United States and Russia expired without a U.S. response to a Russian offer to continue informally abiding by the central limits of the agreement, leaving the two nuclear superpowers with no legally binding curbs on deploying their strategic weapons. The expiration marked the end of an era that began in 1969, when the United States and the Soviet Union launched the SALT I negotiations. For the first time in over half a century, two states holding the overwhelming majority of the world’s nuclear warheads are operating without a shared framework for transparency, verification, or mutual restraint. That is not a diplomatic setback — it is a structural collapse.
The absence of a successor treaty is not simply the result of political friction, though that played its part. In 2019, the United States unilaterally withdrew from the Intermediate-Range Nuclear Forces Treaty, and in 2023, amid its war in Ukraine, Russia effectively suspended participation in New START’s verification systems. Each withdrawal fed the next, dismantling the confidence-building architecture that had taken decades to construct. What remains is a vacuum that both sides are now filling with new weapons programs, strategic posturing, and competing visions of what a successor framework should even measure.
Two Visions, One Impasse
The core difficulty is that Washington and Moscow no longer agree on what “strategic stability” means in practice. The original 1990 US-Soviet definition focused narrowly on preventing a first nuclear strike — ensuring neither side could rationally calculate that a preemptive attack would succeed. That logic was coherent when each side’s primary fear was a massive, decapitating salvo against the other’s nuclear forces. It is far less coherent in a world where the most likely nuclear use scenarios involve regional escalation, conventional precision strikes that inadvertently hit nuclear command infrastructure, or miscalculation driven by dual-use weapons that look nuclear to an adversary’s early-warning system.
The United States has proposed expanding arms control to cover all nuclear warheads — including tactical systems — a position driven in part by concerns about Russia’s large non-strategic arsenal. Russia has countered with what its diplomats call the “security equation”: any new framework must also address conventional precision-guided weapons, missile defenses, and space-based systems. Both positions reflect genuine security concerns. Both also conveniently frame the negotiating agenda in ways that disadvantage the other side. Neither has moved significantly toward the other since 2021.
The technological landscape is making the gap harder to bridge. Modern technologies, including artificial-intelligence-enabled command systems and hypersonic delivery vehicles, increasingly blur the line between conventional and nuclear capabilities. In April 2026, the U.S. Army’s Dark Eagle hypersonic missile was placed under USSTRATCOM command — on par with nuclear-capable delivery systems. Russia announced that the Oreshnik hypersonic ballistic missile had entered production and would be deployed in Belarus, a weapon that can carry conventional or nuclear warheads, reaches speeds up to Mach 10, and covers all of Europe. When the same delivery system can carry either a conventional or nuclear payload, the adversary’s early-warning network cannot distinguish between an attack that demands conventional retaliation and one that demands nuclear response. That ambiguity is not a peripheral problem for arms control — it is the central one.
Why Multilateral Formats Keep Failing
The logical response to a multipolar nuclear environment would be a multilateral arms control process. The P5 format — bringing together the five permanent members of the UN Security Council — has been attempted before and has consistently produced declarations of goodwill rather than binding commitments. The structural reason is straightforward: successful arms control requires mutual deterrence relationships and approximate parity between the negotiating parties. Without both conditions, one side is being asked to legalize its own inferiority, and the stronger party has no incentive to sacrifice its advantage.
China currently holds an estimated 600 nuclear warheads, a figure expected to reach 1,000 by 2030 — a buildup occurring precisely as the arms control regime weakens, with countries withdrawing from treaties and the last remaining U.S.-Russia agreement expired. Although the United States has long invited China to join nuclear arms control negotiations, China has declined, viewing its nuclear forces as insufficient for disarmament talks and interpreting the invitation as a U.S. effort to secure nuclear superiority. Beijing appears to want a nuclear force that looks more like Russia and the United States, which currently control an estimated 86 percent of the world’s nuclear warheads — though reaching that parity would take considerable time.
The bilateral path between Washington and Beijing is theoretically more promising than a five-party format, but it faces its own obstacles. Any bilateral U.S.-China agreement would require Russia to accept a ceiling shared with China — which Moscow has consistently refused, since matching China’s buildup would force Russia to reduce its own deterrent forces. And China has little incentive to negotiate limits before it achieves the parity it is building toward.
What Collapse Actually Risks
The danger of a prolonged legal vacuum is not simply that arsenals grow unconstrained, though they will. With the end of New START, the guardrails that created transparency and prevented a nuclear arms race have ended — and the United States and Russia together possess almost 90 percent of the world’s nuclear weapons. The loss of verification mechanisms means that each side must now plan against worst-case assumptions about what the other is building, which historically drives procurement decisions that the other side then mirrors. That spiral dynamic — familiar from the Cold War — is now operating without the treaty infrastructure that previously interrupted it.
The NPT is under parallel stress. Many states parties to the Treaty on the Non-Proliferation of Nuclear Weapons are dissatisfied with what they perceive as recent steps away from nuclear weapons reductions and an increased salience of nuclear weapons generally. The Comprehensive Nuclear-Test-Ban Treaty remains unratified by key states, and pressure to resume testing grows as verification regimes weaken. Iran’s nuclear posture after Operation Epic Fury has added another unpredictable variable to an already crowded proliferation landscape.
The constructive path forward does not require a single comprehensive treaty — a standard that the current geopolitical environment makes virtually unachievable. It requires sequenced bilateral agreements that build toward multilateral frameworks over time: a US-Russia agreement covering deployed strategic systems as a baseline, parallel US-China discussions on the specific categories of long-range weapons that most concern both sides, and a reinvigorated P5 process for extending limits to regional nuclear states. None of these tracks is easy. All of them are less dangerous than the alternative, which is an unconstrained three-way arms competition among powers that have already demonstrated, in Ukraine and Iran, that conventional conflicts can escalate in ways no one fully anticipated.
Original analysis inspired by Alexey Arbatov and Konstantin Bogdanov from The Bulletin of the Atomic Scientists. Additional research and verification conducted through multiple sources.
By ThinkTanksMonitor
