On February 5, 2026, the New START Treaty, the last remaining bilateral nuclear arms control agreement between the United States and Russia, officially expired.
This marked the end of more than half a century of negotiated limits on the strategic nuclear arsenals of the world’s two largest nuclear powers.
The treaty, originally signed in 2010 and extended for five years in 2021, lapsed at midnight GMT on February 5, as no formal successor agreement or further extension was reached.
Russia had proposed in September 2025 to informally continue observing the treaty’s limits for an additional year, a suggestion to which U.S. President Donald Trump initially responded positively, However, the U.S. did not provide a formal response to the proposal.
In a January 8, 2026, interview with The New York Times, Trump took a more nonchalant stance on the impending expiration, stating: “If it expires, it expires. We’ll just do a better agreement.”
He emphasized pursuing a more comprehensive deal, adding that “you probably want to get a couple of other players involved also,” referring to his long-standing interest in including China in future nuclear arms control talks.
International reactions were swift and concerned. UN Secretary-General António Guterres described the expiry as a “grave moment for international peace and security,” noting that for the first time in over 50 years, there are no binding limits on U.S. and Russian strategic nuclear arsenals.
Experts and organizations, including the International Campaign to Abolish Nuclear Weapons (ICAN), warned of heightened risks of miscalculation, reduced transparency, and a potential new arms race.
The Kremlin expressed regret over the lapse but affirmed Russia’s commitment to act responsibly as a nuclear power.
”The agreement is coming to an end. We view this negatively and express our regret.” He added that Russia would “maintain its responsible and attentive approach to the issue of strategic stability in the field of nuclear weapons” and act in line with national interests.
What was the New START Treaty?
The New START Treaty (formally the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms) was a bilateral agreement between the U.S. and Russia aimed at capping deployed strategic nuclear weapons, those capable of intercontinental range, such as intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and heavy bombers equipped for nuclear armaments.
Key limits included:
• No more than 1,550 deployed strategic nuclear warheads (counting each heavy bomber as one warhead).
• No more than 700 deployed ICBMs, SLBMs, and heavy bombers.
• No more than 800 deployed and non-deployed launchers for these systems.
The treaty entered into force on February 5, 2011, after being signed by then-U.S. President Barack Obama and Russian President Dmitry Medvedev.
Both sides met the central limits by 2018 and largely remained in compliance with the quantitative caps, though verification faced challenges.
It featured robust transparency measures, including biannual data exchanges, notifications on force changes, telemetric information on missile tests, and up to 18 on-site inspections per year (Type One for sites with deployed systems and Type Two for non-deployed).
These mechanisms provided critical insights into each other’s forces, reducing the risk of surprise or miscalculation.
The treaty covered only deployed strategic systems, not non-strategic (tactical) weapons or stored reserves. Estimates indicate Russia possesses around 5,000-5,500 total nuclear warheads and the U.S. around 5,000-5,200, with the treaty constraining only a portion of these arsenals.
What It Means?
With the treaty’s expiration, there are now no legally binding caps on the number of deployed strategic nuclear warheads or delivery systems the U.S. and Russia can maintain.
This removes a key pillar of global strategic stability, as the two nations account for over 90% of the world’s nuclear weapons.
Verification and transparency mechanisms have ceased, meaning no more mandatory on-site inspections, data exchanges, or notifications, leading to reduced mutual understanding of each side’s capabilities and intentions.
Experts warn this could fuel mistrust, increase the risk of nuclear use through miscalculation, and accelerate modernization or expansion of arsenals amid ongoing geopolitical tensions, including the war in Ukraine and China’s growing nuclear capabilities (estimated at around 600 warheads).
While both sides have indicated they do not plan immediate massive buildups, due to logistical, financial, and strategic constraints, the absence of limits raises the specter of a renewed arms race.
Russia has suspended compliance elements since 2023, and the U.S. reciprocated in information sharing. Some reports suggest informal understandings or short-term observances might emerge from ongoing talks, but no firm commitments have been confirmed as of February 5, 2026.
The broader obligation under the Nuclear Non-Proliferation Treaty (NPT) for nuclear-weapon states to pursue disarmament remains in force, with the next NPT Review Conference scheduled for April-May 2026 offering a potential forum for progress.
Groups like ICAN emphasize the role of the Treaty on the Prohibition of Nuclear Weapons (TPNW) in stigmatizing nuclear arms and pressing for disarmament.
The expiry underscores a dangerous shift: the world now faces higher nuclear risks without the guardrails that helped prevent escalation for decades.
Urgent diplomacy will be essential to restore verifiable limits and prevent unchecked proliferation.
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