Last nuclear weapons limits expired – pushing world toward new arms race

The expiration of the New START treaty removes nuclear limits between the U.S. and Russia, risking an unpredictable arms race amidst growing tensions with China, increasing the chance of nuclear conflict.

For the first time in more than half a century, there are no binding restraints on the buildup of the largest nuclear forces on Earth. The New START treaty expired on Feb. 5, 2026, ending the last agreed limits on U.S. and Russian nuclear forces.

New START limited the number of strategic nuclear weapons the United States and Russia could deploy to 1,550 each. It also limited the missiles and bombers those warheads were loaded on, required on-site inspections and data exchanges, barred interference with satellite monitoring, and established a joint commission to discuss disputes. It did not limit the number of nuclear weapons each side could hold in reserve.

With China rapidly building up its nuclear forces, intense rivalry between the United States, China and Russia, and evolving technologies – from precision conventional weapons to artificial intelligence complicating nuclear balances – there is a real potential of an unpredictable three-way nuclear arms competition.

Such a competition could increase the danger of nuclear conflict, which I believe is higher than it has been in decades.

While the particular numbers of warheads and delivery vehicles an accord specifies may not make an immense difference, nuclear agreements offer important advantages in four key areas:

After 1962’s Cuban missile crisis, President John F. Kennedy realized that relying on nuclear deterrence without any agreed nuclear restraints or risk-reduction measures is just too dangerous. He moved quickly to negotiate the Limited Test Ban Treaty in 1963 and put in place a U.S.-Soviet hotline for crisis communication.

Moreover, the countries that have promised not to get nuclear weapons under the Nuclear Nonproliferation Treaty want to see the nuclear-armed nations living up to their treaty obligation to negotiate in good faith toward nuclear disarmament. As pressure builds for countries to get their own nuclear weapons, maintaining the nonproliferation regime and getting the non-nuclear countries’ votes for stronger nuclear safeguards or export controls is likely to require the nuclear-armed nations to accept at least some constraints of their own.

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