The New START Treaty, the only agreement imposing numerical limits on the US and Russian strategic nuclear arsenals, expired on February 5. Since 2011, New START has capped each side’s deployed nuclear forces at 1,550 warheads and 700 delivery vehicles. It has also required data exchanges about each side’s weapons, verification inspections by each side’s arms control experts, and a reciprocal commitment not to interfere with each side’s ability to remotely surveil the other’s arsenal, such as with spy satellites. Russia stopped complying with the data exchange and verification provisions of the treaty after it invaded Ukraine. Both sides still observe the quantitative limits, however, conferring some predictability on the world’s largest nuclear forces.

In September, Russian President Vladimir Putin offered US President Donald Trump an informal extension of Russia’s adherence to these limits for another year if the United States agrees to do the same. The White House should agree. The end of New START compliance would increase the chances of an unnecessary nuclear buildup and might complicate the negotiation of a successor treaty. It also runs contrary to Trump’s consistent record of calling nuclear war the “greatest existential threat” and public support for arms control.

Trump should take Putin’s offer seriously. Nuclear arsenals cannot be changed overnight, so there may still be time to talk after the February 5 expiration. The United States should counteroffer for an informal one-year extension of all New START provisions, including restarting data exchanges and verification visits.

China’s Nuclear Weapons Are a Concern—but Not an Immediate One

The most salient argument against an extension is that the president must respond to China’s emergence as a third nuclear superpower alongside Russia and the United States. China’s arsenal has grown from 200 warheads in 2020 to around 600 today, and the Pentagon estimates it will hit 1,000 by 2030. US defense planners worry about this buildup because of its implications for the United States’ own damage limitation nuclear strategy. This requires the US military to have the ability to target adversary nuclear forces to limit the damage they can inflict on the homeland in the event of a nuclear war. The Trump administration insists that China be involved in any successor to New START, but China has made clear that it is unwilling to engage in quantitative discussions of limitations while its arsenal remains smaller than either America’s or Russia’s.

Damage limitation is supposed to improve the credibility of US nuclear defense commitments to its allies, but it involves unappealing trade-offs. Most importantly, it leads to an arms race logic with no clear end, particularly when the United States faces two large nuclear arsenals, not just Russia’s. As Russia and China expand their arsenals, US policymakers feel pressure to build up America’s stockpile to secure a chance at targeting their additional nuclear forces. Rivals then feel the need to build up even more.

Damage limitation also generates destabilizing “use them or lose them” pressures, in which adversaries may be tempted to launch their nuclear weapons if they fear the United States is about to destroy them. And damage limitation may not be feasible in the first place. Some weapons are still likely to get through, especially if the adversary in question is a nuclear peer like Russia. As even a few successful strikes could inflict society-altering damage on the United States, the practical advantage of this strategy is questionable at best.

The existing fleet of US nuclear missiles and bombers have enough spare capacity to be “uploaded” with up to 1,900 additional warheads currently in storage, which would more than double the current deployed force. This process would take less than a year to complete, but Russia would almost certainly react with its own upload, which could almost double its deployed arsenal. Even taking damage limitation targeting as a given, the United States does not need to upload in the next 12 months—years before China approaches parity.

Despite Its Problems, New START Is the Best Short-Term Safeguard

Renewing the New START requirements would preserve some certainty about Russia’s nuclear intentions for an additional year and avoid compounding the problem of “known unknowns.” If the treaty terms fully lapse, American policymakers would immediately have to plan against two large and growing strategic arsenals, not just one. The United States is already in the midst of a $1 trillion, 30-year nuclear modernization program. It should be trying to avoid a new arms race, which would further strain its industrial and fiscal resources.

In an unsettled global nuclear landscape, an extension would also preserve important quantitative and verification benchmarks. Negotiations for a successor treaty might be more predictable and smoother if there were an in-force collection of behaviors and standards to build upon. Crucially, keeping the existing limits in place might serve as a useful wedge between China and Russia. The retention of a US-Russian accord may loosen Sino-Russian coordination regarding a successor treaty. Important, too, for the Trump administration is that extension is popular with American voters.

If the Trump administration strikes a year-long extension deal, how should it use that year? First, it should develop and fund a plan to begin to upload warheads in 2027, should that become necessary. Second, it should continue its efforts to achieve a settlement between Russia and Ukraine, a development that would eliminate a major obstacle to future nuclear talks. Finally, US policymakers should reconsider their pursuit of a nuclear damage limitation capability and the closely related Golden Dome missile defense system. Both Russia and China could likely build enough missiles to overwhelm it. These policies could make Russia and China reluctant to sign future quantitative arms control treaties with the United States.

A year-long informal extension of all New START provisions would sustain important arms control practices and buy time and stability for diplomacy to determine what comes next. Otherwise, 2026 might unnecessarily kick off a prolonged strategic arms competition that would ultimately harm US interests.

Sealing an eventual successor to New START will require restraint and imagination. Extending New START is an opportunity to begin the groundwork. President Trump should seize it.