Lead: The last major nuclear arms-control pact between the United States and Russia, the 2010 New START treaty, is due to expire on Thursday, raising urgent concerns about a renewed nuclear arms race. The accord limited deployed strategic warheads to 1,550 per side and included verification measures such as data exchanges and on-site inspections. Its lapse would effectively halt the core bilateral transparency that has helped manage U.S.-Russia nuclear competition since the Cold War. Policymakers and analysts warn the end of the treaty could increase mistrust, accelerate weapon modernisation, and reduce warning time for crisis managers.
Key Takeaways
- The New START treaty, signed in 2010, capped deployed U.S. and Russian strategic nuclear warheads at 1,550 each and included inspections and notifications.
- Russia suspended the treaty three years ago amid tensions over the Ukraine war, though both sides had been largely observed to follow its limits.
- Its expiry follows the collapse or erosion of several arms-control frameworks, including the INF, Open Skies, and the CFE treaties.
- Both Russia and the U.S. are modernising strategic forces; new systems cited include Russia’s Poseidon and Burevestnik and hypersonic programmes in multiple countries.
- U.S. officials say any future deal should include China; Russia counters that European nuclear powers France and the UK must be considered.
- Senior military and security figures warn the unraveling of treaty architecture increases global instability and the risk of miscalculation.
Background
Arms-control agreements between the United States and Russia grew from the superpower détente that followed the Cold War. The original START, signed in 1991, limited deployed warheads to roughly 6,000 per side and established verification routines designed to reduce surprise and misperception. New START, negotiated and signed in 2010 in Prague, reset limits to 1,550 deployed strategic warheads each and created a regime of data exchanges, notifications, and on-site inspections intended to give leaders clearer insight into each other’s forces. Over the last decade, those verification steps became a backbone of strategic stability, permitting reductions while preserving confidence that limits were respected.
Since 2019–2022 a series of bilateral and multilateral arms-control instruments has deteriorated or been abandoned. The 1987 Intermediate-Range Nuclear Forces (INF) Treaty, which eliminated a class of short- and medium-range ground-launched missiles in Europe, collapsed first; the Open Skies Treaty, allowing reciprocal aerial observation flights, also ended for many participants; and the Conventional Armed Forces in Europe (CFE) Treaty has been effectively sidelined by political disputes. Critics say that losing these instruments removed important channels for risk reduction and transparency, leaving nuclear posture choices more opaque.
Main Event
The New START treaty is formally set to lapse on Thursday unless Washington and Moscow reach an agreement to extend or replace it. The treaty’s central limits applied to deployed strategic warheads and delivery systems and were backed by verification measures designed to prevent surprise escalations. Russian officials announced a suspension of the treaty three years ago in the context of the Ukraine war; despite that step, analysts continued to assess that both parties were broadly complying with limits until now.
In recent days, senior Russian and American statements have signalled divergent approaches. Kremlin-aligned voices, including former Russian president Dmitry Medvedev, warned that the treaty’s expiration should alarm observers, while a Russian foreign ministry statement framed Moscow as free to choose ‘‘next steps’’ but said Russia would act ‘‘responsibly and in a balanced manner.’’ In the United States, then-President Donald Trump told the New York Times last month: “If it expires, it expires… We’ll just do a better agreement,” signaling a willingness to move on absent a new deal that meets U.S. priorities.
Pope Leo urged renewal of the treaty this week, saying world circumstances required doing everything possible to avert a new arms race. Military officials and analysts in Europe, including former UK Chief of the Defence Staff Admiral Sir Tony Radakin, have warned that the collapse of these frameworks is one of the most dangerous aspects of current global security, citing a rising prominence of nuclear forces. Experts at think tanks such as RUSI highlight that both sides have technical drivers to continue expanding certain strategic capabilities, complicating rapid diplomacy.
The lapse comes as all three leading nuclear powers are modernising arsenals. Russia has been developing systems it describes as capable of penetrating defences—examples cited by analysts include the Poseidon nuclear-powered torpedo and the Burevestnik nuclear-powered cruise missile. The U.S., Russia and China are also investing in long-range hypersonic weapons capable of manoeuvring at speeds above 4,000 mph (6,437 km/h), increasing the challenge of detection and interception and shortening decision windows in crises.
Analysis & Implications
The expiry of New START would reduce formal transparency and verification between the two largest nuclear arsenals, increasing the risk that misunderstandings or technical anomalies could be misread as aggressive moves. Without data exchanges and inspections, national estimates of deployed warheads and delivery systems will be less certain, making timely crisis assessment harder for political leaders and military planners. That uncertainty can raise incentives for rapid deployments or alerting measures that, in turn, elevate the risk of inadvertent escalation.
Geopolitically, the treaty’s end could accelerate a multipolar arms dynamic. The U.S. insists China be included in future negotiations because Beijing is increasing its strategic forces; Russia argues any multilateral bargain should also consider France and the UK. These competing positions reflect deeper strategic divergences: Washington seeks broader constraints; Moscow seeks parity considerations that reflect multiple nuclear actors in Europe and Asia.
Economically and industrially, resuming an unconstrained build-up would drive major defence procurement programmes and shift budgets toward strategic systems, with implications for national spending priorities. For allied states and regional neighbours, reduced U.S.-Russia communication channels could spur hedging—new deployments, deeper integration within alliances, or acceleration of domestic strategic capabilities—creating fresh security dilemmas across Europe and Asia.
Comparison & Data
| Treaty | Year | Key effect |
|---|---|---|
| START I | 1991 | ~6,000 deployed warheads cap (each side) |
| New START | 2010 | 1,550 deployed strategic warheads cap (each side) |
| INF Treaty | 1987 | Eliminated most land-based missiles of 500–5,500 km in Europe |
| Open Skies | 1992 | Reciprocal unarmed surveillance flights |
These instruments reduced uncertainty by setting quantitative limits and creating verification routines. With New START gone, the gap in bilateral controls will be the most consequential because it directly restrained the largest deployed strategic arsenals with an enforceable inspection regime. Analysts note that treaty caps do not alone prevent modernisation, but they did slow qualitative competition by ensuring mutual visibility.
Reactions & Quotes
Officials and analysts offered measured, sometimes contrasting reactions to the treaty’s imminent lapse.
“This expiration should alarm everyone.”
Dmitry Medvedev (former Russian president)
Context: Medvedev, who signed the 2010 treaty for Russia as president, framed the lapse as a worrying milestone. His remark comes amid assertive Russian rhetoric about strategic weapons but was paired with other official lines emphasizing a pledge to act in a measured way.
“If it expires, it expires… We’ll just do a better agreement.”
Donald Trump (then U.S. president)
Context: The quoted line to the New York Times signals Washington’s posture that it prefers a broader or updated deal but is willing to let the current agreement lapse if terms are not met. U.S. officials have stressed China’s inclusion as a central demand for future talks.
“The collapse of these key arms control treaties is one of the most dangerous aspects of our current global security.”
Admiral Sir Tony Radakin (former UK Chief of Defence Staff)
Context: Britain’s former military head warned that unraveling treaty architecture raises the prominence of nuclear weapons and complicates allied defence planning across Europe, reflecting broader institutional concerns about stability management.
Unconfirmed
- Whether either side will undertake rapid, large-scale redeployments of strategic forces immediately after expiry is not verified and remains speculative.
- Claims that a new multilateral treaty including China, France, and the UK is imminent are unverified; negotiating positions remain publicly unresolved.
Bottom Line
The expiry of New START removes a central pillar of U.S.-Russia strategic transparency and raises the prospect of less predictable nuclear competition. While neither side has yet signalled an immediate, large-scale arms explosion, the loss of inspections and data exchange will increase uncertainty and could shorten decision times in crises. Policymakers face a narrowing window to negotiate extensions or alternatives that restore measurable limits and verification before risk dynamics harden.
In the weeks and months ahead, observers should watch for concrete diplomatic initiatives, public signalling on force posture, and any additional steps to widen the negotiating table to other nuclear powers. Restoring durable stability will require technical verification measures, political will, and convergence on which states must be included—requirements that are technically complex and politically contested but necessary to avoid a more dangerous era of unconstrained nuclear competition.