The final remaining nuclear treaty between the United States and Russia is scheduled to lapse on Thursday, eliminating longstanding restrictions on the world’s two largest nuclear stockpiles for the first time in over fifty years.

The expiration of the New START agreement could spark fears of a renewed, uncontrolled nuclear arms race between global powers.

Russian President Vladimir Putin has expressed willingness to maintain the treaty's limits for one more year, provided the U.S. does the same. However, former U.S. President Donald Trump had not committed to an extension.

A White House official stated that while Trump supported maintaining nuclear limits and including China in discussions, he would decide on any arms control measures independently and without a set timeline.

China, which possesses a smaller but expanding nuclear capability, has shown resistance to joining such agreements.

Kremlin spokesman Dmitry Peskov warned that the world would become “more dangerous” if the U.S. and Russia no longer have nuclear restrictions.

Experts advocating for arms control have long cautioned that letting New START expire could set off a renewed arms build-up, increase geopolitical tensions, and raise the threat of nuclear war.

Daryl Kimball, head of the Arms Control Association, noted the treaty's end would create an environment where both nations could expand their nuclear deployments significantly, for the first time in decades. He warned that this situation could draw China into the race as well.

Kingston Reif, a researcher at the RAND Corporation and former U.S. defense official, emphasized in a recent discussion that without treaty oversight, both sides may ramp up their arsenal out of caution or to gain leverage in potential future negotiations.

Since the start of the Ukraine conflict in early 2022, Putin has frequently highlighted Russia's nuclear capabilities, even revising the country’s nuclear strategy in 2024 to lower the threshold for potential use.

Signed in 2010

The New START Treaty was established in 2010 by then-U.S. President Barack Obama and Russian President Dmitry Medvedev. It limited both nations to no more than 1,550 deployed nuclear warheads and no more than 700 delivery systems, such as missiles and bombers.

Though it was originally set to end in 2021, both sides agreed to a five-year extension. The treaty also provided for detailed, on-site inspections, which were paused in 2020 due to the pandemic and were never reinstated.

In 2023, Putin announced that Russia was halting its participation in the treaty, stating that U.S. inspections were unacceptable during ongoing hostilities in Ukraine. However, Russia pledged to adhere to the treaty's limits despite suspending formal involvement.

In a bid to open the door for future negotiations, Putin offered in September to continue observing the treaty’s terms for another year. He warned that allowing the agreement to lapse completely would boost nuclear proliferation and reduce global security.

Rose Gottemoeller, a U.S. negotiator involved in drafting New START and previously a top NATO official, said a one-year extension would not interfere with U.S. efforts to address China's growing nuclear capability.

Previous pacts

The New START agreement was preceded by decades of arms control treaties between Washington and Moscow, starting with the SALT I agreement signed in 1972 by U.S. President Richard Nixon and Soviet leader Leonid Brezhnev.

That same year, the two nations signed the Anti-Ballistic Missile Treaty, which stayed in effect until 2001 when U.S. President George W. Bush withdrew from it, despite objections from Russia. Moscow viewed such actions as undermining strategic stability and its ability to deter threats.

In response, Putin ordered the development of advanced weapons such as the Burevestnik nuclear cruise missile and the Poseidon underwater nuclear drone. Russia has since claimed successful tests of these systems and intentions to deploy them.

Another key treaty, the Intermediate-range Nuclear Forces Treaty signed in 1987, was terminated in 2019. This accord had banned land-based missiles of certain ranges due to their destabilizing nature and the limited time they allowed for counteraction.

In late 2024 and again recently, Russia used a standard version of its Oreshnik intermediate-range missile against Ukraine. Moscow reports the missile has a capacity to deliver nuclear or conventional warheads over distances up to 5,000 kilometers, making it capable of hitting most of Europe.

Trump’s ‘Golden Dome’

After the end of the treaty, Russia promises to respond strongly to any perceived new threats, according to Medvedev, a former president and current deputy chair of Russia’s Security Council.

Medvedev pointed to former President Trump’s proposed Golden Dome missile defense plan as cause for concern, noting that such initiatives could provoke reactions and disrupt strategic parity.

Kimball explained that this plan is likely to prompt both Russia and China to increase their offensive capabilities to overwhelm any proposed U.S. defensive system, as building offensive weapons is often faster and less expensive than deploying advanced defense technologies.

Further tensions arose after Trump suggested in October 2024 that the U.S. might resume nuclear testing for the first time since 1992. Russia, which last tested in 1990, warned it would mirror such actions if the U.S. carried out nuclear detonations, even though such tests are banned by an international agreement signed by both countries.

U.S. officials clarified that any future tests would not involve actual nuclear explosions. Yet, Kimball warned that restarting tests would seriously damage global nuclear stability and risk encouraging countries like China and India to follow suit.

He concluded by saying that this scenario points toward a new, highly volatile era in nuclear relations among major powers, with increasing competition and a growing threat of conflict unlike anything seen in decades.

Reporting contributed by Michelle L. Price in Washington.

Funding for nuclear security reporting is provided by the Carnegie Corporation of New York and the Outrider Foundation. The Associated Press retains full editorial control over its content.