Why the New START nuclear treaty matters

The final barrier preventing an unlimited nuclear arms race between Washington and Moscow hangs by a thread. With an expiration date looming this year and international inspections suspended, the world faces a precarious future regarding the containment of strategic weapons. Should we be worried?

The New Strategic Arms Reduction Treaty, commonly known as New START, represents the sole remaining diplomatic tether between the world’s two largest nuclear powers - Russia and the United States.

As the clock ticks toward the treaty's absolute expiration 5 February 2026, policymakers are scrambling to understand the implications of a world without nuclear guardrails.

Signed in 2010, the agreement was designed to inject transparency and predictability into the relationship between the U.S and the Russian Federation. 

While other nuclear-armed nations exist, such as China, the UK, France, India, Pakistan, and North Korea, they are not signatories to this specific New START pact. This bilateral focus is born of historical necessity; Washington and Moscow collectively possess approximately 90% of the world’s total nuclear inventory.

It limits both nations to 1,550 deployed strategic nuclear warheads each, a significant reduction from Cold War highs.

It also restricts the number of deployed missiles and bombers to 700, with a total cap of 800 deployed and non-deployed launchers.

Transparency

For more than a decade, the treaty allowed for on-site inspections. American teams could inspect Russian silos, and Russian teams could inspect American submarine bases. 

This transparency meant that neither side had to assume the worst about the other’s intentions.

By capping the arsenals, the treaty also saved both nations billions of dollars that would otherwise have been spent on spiralling defence programmes to counter imaginary threats. 

Why the treaty is in danger

In February 2023, President Vladimir Putin formally announced that Russia was suspending its participation in the treaty. While Moscow stated it would continue to observe the numerical caps on warheads voluntarily, it ceased all inspection activities and stopped sharing data.

The Kremlin’s logic is rooted in what diplomats call "linkage": Russia argues that the U.S. cannot expect to inspect Russian nuclear bases while simultaneously providing weaponry to Ukraine that could be used to strike Russian territory.

This suspension left Washington effectively blind regarding the current status of Russia’s nuclear forces and to encourage Moscow to return to compliance, Washington has also withheld its data updates.

Without an active treaty to extend or replace, the caps will lift, potentially triggering an unrestricted arms race.

Meanwhile, China is rapidly expanding its own nuclear arsenal, complicating the traditional bilateral dynamic. Beijing is estimated to possess around 600 nuclear warheads, making it the world’s third-largest nuclear power, and is modernising its delivery systems, including intercontinental ballistic missiles, nuclear-armed submarines and strategic bombers. U.S. defence assessments project China’s stockpile could exceed 1,000 warheads by 2030.

Washington has repeatedly said any future arms control framework must eventually include China. Beijing, however, says it will not join nuclear arms talks “at this stage,” arguing that its arsenal remains far smaller than those of the United States and Russia.

China has also stressed its opposition to sanctions pressure and the threat of force in nuclear diplomacy. On Thursday, Assistant Foreign Minister Liu Bin told Iran’s deputy foreign minister in Beijing that China “supports Iran’s legitimate right to the peaceful use of nuclear energy” and “opposes the threat of force and sanction pressure.” He added that China will “continue to promote the proper resolution of the Iranian nuclear issue” through dialogue, according to a statement from the Chinese foreign ministry.

• New START expiry risks unpredictability and loss of nuclear limits, analyst warns
• Russia ready for world without nuclear arms limits after New START expiry, senior diplomat says

Proposed solutions

The primary proposal from arms control advocates is an unconditional extension or a temporary ‘bridging agreement’ that maintains the 1,550 warhead limit informally, even if inspections remain paused. This would buy time for the political climate to cool.

A second solution involves compartmentalisation, where both nations agree to treat nuclear safety as a separate issue from the war in Ukraine. However, this requires political will.

A third, more complex proposal is the inclusion of China in future frameworks. The U.S. has long argued that the next treaty must be trilateral. However, Beijing has consistently rejected this, citing its much smaller arsenal compared to the superpowers.

Consequently, the most likely immediate solution being prepared by defence planners is to return to unilateral deterrence, where the West increases its arsenal to match the combined threat of Russia and China, signalling the definitive end of the post-Cold War arms control era.

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