For the first time in more than five decades, the world’s two largest nuclear powers are operating without a single legally binding limit on their strategic arsenals. New START, the last remaining US-Russia arms control treaty, expired on February 5, 2026, marking one of the most significant setbacks for arms control and disarmament in modern history.
Background
Arms control in international relations refers to the set of agreements, treaties, and verification mechanisms that states use to limit the development, testing, and deployment of weapons, particularly weapons of mass destruction. The practice traces back to early Cold War efforts like the 1963 Partial Test Ban Treaty and the 1968 Nuclear Non-Proliferation Treaty, and it later expanded through decades of arms control treaties between Washington and Moscow.
New START, signed in 2010 by President Barack Obama and Russian President Dmitry Medvedev, limited each country to 1,550 deployed strategic nuclear warheads and 700 deployed delivery systems, including intercontinental ballistic missiles, submarine-launched missiles, and long-range bombers. It also required regular data exchanges and on-site inspections, giving both countries verified insight into each other’s nuclear forces.
Russia suspended its participation in the treaty in February 2023, citing tensions over the war in Ukraine, and on-site inspections effectively stopped even earlier, during the Covid-19 pandemic. The treaty could only be extended once under its own terms, meaning its scheduled expiration on February 5, 2026, always loomed as a deadline unless a new agreement replaced it.
Details
In the months leading up to expiration, Russian President Vladimir Putin proposed that both countries continue voluntarily observing New START’s central limits for one additional year, even without a formal verification regime. Washington did not respond to that offer before the deadline passed, and the treaty lapsed without a replacement in place.
Organizations tracking arms control and disarmament, including the Arms Control Association, have described the moment as historic and troubling. Both countries retain far larger total nuclear stockpiles than New START ever covered, with Russia estimated to hold roughly 5,459 warheads and the United States around 5,177, though only the deployed strategic portion of those arsenals was ever subject to treaty limits.
The timing carries added weight because the expiration comes just ahead of the 2026 Nuclear Non-Proliferation Treaty Review Conference, where nuclear-armed states are expected to show progress on disarmament commitments under Article VI of that treaty. Analysts say the collapse of the last US-Russia arms control agreement sends the opposite signal at a particularly sensitive moment.
China’s expanding nuclear arsenal has further complicated the picture. President Trump has said he wants any future arms control treaties to include Beijing and to cover Russia’s full nuclear stockpile rather than just deployed strategic warheads, goals he also pursued unsuccessfully during his first term in office.
For students and researchers looking for grounding in the subject, resources like an arms control PDF summary or an arms control PPT slide deck from organizations such as the Arms Control Association remain widely used teaching tools, since New START’s collapse has renewed academic and policy interest in how earlier arms control treaties were negotiated and structured.
Quotes
The Arms Control Association has described New START as the first verifiable US-Russian nuclear arms control treaty since the original START agreement in 1994, and noted that its expiration ends more than three decades of continuous, verifiable limits on the two countries’ strategic arsenals.
Analysts at the Council on Foreign Relations noted that inspections had already stopped years before the formal expiration, arguing that some observers see the treaty’s end less as a sudden collapse and more as the closing line of a story that had effectively already been written.
Researchers at the Vienna Center for Disarmament and Non-Proliferation described Putin’s proposal to continue observing the treaty’s limits informally as largely symbolic, but said it was nonetheless a desirable gesture given the sensitivity of the upcoming Non-Proliferation Treaty review.
Impact
The global impact of New START’s expiration is significant. For the first time since the early 1970s, there is no legally binding cap on US and Russian strategic nuclear forces while no active negotiations are underway for a replacement, a break from decades of continuous, if imperfect, restraint between the two nuclear superpowers.
The ripple effects extend beyond the bilateral relationship. With China continuing to expand and modernize its own nuclear forces, the absence of any US-Russia constraint weakens the broader international case for restraint and could reinforce a shift toward open-ended nuclear competition among multiple powers rather than a return to structured arms control.
Some US allies had hoped for even a symbolic one-year extension of New START’s limits, viewing it as a signal that Washington and Moscow were not abandoning arms control architecture altogether. Its absence may also complicate discussions at the Non-Proliferation Treaty Review Conference, where nuclear states are expected to demonstrate credible progress on disarmament.
Conclusion
With no treaty currently governing US and Russian strategic nuclear forces, the coming months will test whether the two countries pursue any form of successor arrangement, formal or informal. President Trump has expressed interest in a broader agreement that includes China, though similar ambitions during his first term did not result in a finalized deal.
For now, the field of arms control and disarmament is in uncharted territory. Organizations like the Arms Control Association continue to monitor developments closely and push for renewed dialogue between the world’s major nuclear powers.
Frequently Asked Questions
Who has 90% of the world’s nuclear weapons?
The United States and Russia together hold approximately 90 percent of the world’s nuclear warheads, a dominance that dates back to the Cold War arms race between the two superpowers. Current estimates put Russia’s total stockpile at roughly 5,459 warheads and the United States at around 5,177, dwarfing the arsenals of the other nuclear-armed states, including China, France, the United Kingdom, Pakistan, India, Israel, and North Korea. This concentration of nuclear weapons in just two countries is precisely why treaties like New START have historically carried such outsized importance in global arms control and disarmament efforts, since bilateral US-Russia agreements have directly constrained the vast majority of the world’s nuclear arsenal.
What does disarmament mean?
Disarmament refers to the reduction, limitation, or complete elimination of weapons, particularly weapons of mass destruction like nuclear, chemical, and biological arms, typically pursued through international treaties and verification agreements. It differs slightly from arms control, which focuses more broadly on managing and regulating weapons development and deployment without necessarily requiring their elimination. Disarmament efforts are often associated with organizations like the United Nations Office for Disarmament Affairs and are formally embedded in agreements such as the Nuclear Non-Proliferation Treaty, which commits nuclear-armed signatories under Article VI to pursue negotiations in good faith toward eventual nuclear disarmament, a commitment now under renewed scrutiny following New START’s expiration.
Who has control of nuclear weapons?
Control over nuclear weapons rests with each individual nuclear-armed state’s national government, typically concentrated in the hands of a head of state or a small designated command authority responsible for authorizing their use. In the United States, the president holds sole authority to order a nuclear strike, working through the military chain of command, while in Russia, similar centralized authority rests with the president alongside senior military leadership. Internationally, there is no single global body with direct control over any country’s nuclear arsenal, which is precisely why arms control treaties like New START have historically served as the primary mechanism for constraining how many weapons major powers deploy and how transparently they operate, rather than any form of shared or supranational control.
