Barring last-minute nuclear deal, US and Russia teeter on brink of new arms race

The United States and Russia are on the brink of an unrestrained nuclear arms race for the first time since the Cold War unless they reach a last-minute agreement before their final remaining arms control treaty expires in less than a week.

The New START treaty, which limits long-range nuclear arsenals, is due to expire on February 5. Without a replacement or extension, there would be no formal constraints on US and Russian strategic nuclear forces for the first time since 1972, when Washington and Moscow signed their first arms limitation accords.

Russian President Vladimir Putin has proposed that both sides adhere to existing missile and warhead limits for one more year to allow time for negotiations. US President Donald Trump has not formally responded.

Read More: Putin proposes one-year extension of US-Russia nuclear arms pact

“If it expires, it expires,” Trump said this month, adding that the treaty should be replaced with a better agreement.

Some US lawmakers and analysts argue Trump should reject Putin’s offer, freeing Washington to expand its arsenal to counter China’s rapidly growing nuclear forces. Trump has said he wants to pursue “denuclearisation” talks with both Russia and China, but Beijing says it is unreasonable to expect it to join negotiations while its arsenal remains far smaller than those of the two Cold War rivals.

Why nuclear treaties matter

Since the height of the Cold War, when the US and the Soviet Union threatened each other with “mutually assured destruction”, arms control treaties have been seen as a way to prevent catastrophic miscalculation and an economically ruinous arms race.

Beyond numerical limits, such agreements require transparency measures, including data exchanges and inspections. These channels help each side understand the other’s intentions, said Darya Dolzikova of the Royal United Services Institute in London.

Without a treaty, both sides would be forced to plan based on worst-case assumptions, said Nikolai Sokov, a former Soviet and Russian arms negotiator.

“It’s a self-sustaining kind of process,” Sokov said.

“If you’ve got an unregulated arms race, things will get quite destabilising.”

Replacing new start, no simple task

Since the collapse of the Soviet Union, Washington and Moscow have repeatedly replaced Cold War-era arms control agreements. New START, signed in 2010 by then US President Barack Obama and Russia’s then-president Dmitry Medvedev, caps deployed strategic warheads at 1,550 per side and limits delivery systems to 700.

Negotiating a successor would be complex. Russia has developed new nuclear-capable systems, including the Burevestnik cruise missile, the hypersonic Oreshnik and the Poseidon nuclear torpedo, which fall outside New START’s framework.

Trump has also announced plans for a space-based “Golden Dome” missile defence system, which Moscow views as a threat to strategic stability.

At the same time, China’s nuclear arsenal is expanding without constraint. Beijing is estimated to have about 600 warheads, and the Pentagon projects that number could exceed 1,000 by 2030.

A bipartisan US congressional commission warned in 2023 that Washington now faces an “existential challenge” from two nuclear peers and should prepare for the possibility of simultaneous conflicts with Russia and China.

Its recommendations included the option of redeploying nuclear warheads placed in reserve under New START, potentially restoring warheads to Minuteman III intercontinental ballistic missiles, submarine-launched Trident D5 missiles and some B-52 bombers converted to conventional roles.

“The warheads are there. The missiles are there. You’re not buying anything new,” said a former senior US official involved in nuclear policy, speaking on condition of anonymity.

At the high end, the US could nearly double its deployed warheads from New START levels, while Russia could add around 800, said Kingston Reif, a former Pentagon official now with RAND. Significant changes would take at least a year, he said.

Putin’s offer divided US opinion

US policy circles are split on whether Trump should accept Putin’s proposal to extend current limits.

Paul Dean of the Nuclear Threat Initiative said maintaining limits would reduce the risk of a costly arms race and dangerous misinterpretation during a crisis.

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Arms control advocates also point to the cost of modernising US nuclear forces. The Congressional Budget Office estimates nearly $1 trillion will be spent between 2025 and 2034 to sustain and upgrade the arsenal.

“If the US exceeds New START limits, Russia will do the same, and China will use it as justification to build up its arsenal,” Democratic Senator Ed Markey told Reuters.

Others argue Washington cannot trust Putin, noting that Russia suspended New START inspections in 2023 over US support for Ukraine.

Franklin Miller, a member of the bipartisan commission, said the US must expand its deployed nuclear forces to deter both Russia and China simultaneously.

“The force that the treaty confined the US to in 2010 is not sufficient,” Miller said, though he added any increase should be gradual.

Asked about Trump’s intentions, a White House official said: “The president will decide the path forward on nuclear arms control, which he will clarify on his own timeline.”