U.S.-Russia Treaty Expires: Era of Unchecked Nuclear Proliferation Is Perilous

Editorial

16:30 JST, February 7, 2026

The New START Treaty — a nuclear disarmament framework between the United States and Russia that is formally known as the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms — expired on Thursday.

As the restraints that held back the two nuclear powers have ceased to exist, concerns have arisen that moves for nuclear buildups and development could spread to other countries.

The treaty came into force in 2011. It limited the number of each side’s deployed nuclear warheads, such as those capable of being mounted on long-range ballistic missiles to strike an adversary’s core targets, to 1,550, while calling for mutually conducting on-site inspections and sharing information, among other measures.

The termination of the treaty could result in a return to an arms race between the United States and Russia, with both nations lacking effective mutual communication.

The United States and the Soviet Union, since succeeded by Russia, engaged in a nuclear arms race during the Cold War with their combined stockpiles reaching about 70,000 warheads. Toward the end of the Cold War, they moved closer on arms reduction, and the total number of their warheads is estimated to have fallen to just over 10,000 as of January last year. It is regrettable that the treaty’s expiration has brought an end to decades of such disarmament progress.

The United States and Russia possess 90% of nuclear weapons in the world. Meanwhile, China has been rapidly expanding its nuclear arsenal and is believed to already possess 600 warheads. There is an estimate that this number could reach 1,000 by 2030.

After the New START Treaty’s expiration, U.S. President Donald Trump argued that a new treaty should be formulated. He has also claimed that a new nuclear reduction framework needs to involve China in addition to the United States and Russia. It is reasonable to think that some form of constraints is essential on China, which has been outside the framework of such a treaty.

However, China has refused to negotiate, saying the number of its nuclear arms is far fewer than those of the United States and Russia. Trump is scheduled to visit China in April for talks with Chinese President Xi Jinping. During the visit, Trump should strongly urge Xi to participate in negotiations on arms reduction.

The United States and Russia have not only allowed the New START Treaty to expire but have even made moves against nuclear arms reduction.

Russian President Vladimir Putin has continued to threaten Ukraine with nuclear weapons. In autumn last year, he announced that Moscow had successfully conducted testing of new weapons capable of carrying nuclear warheads. Also, Trump has ordered a resumption of nuclear testing.

The Nuclear Nonproliferation Treaty (NPT), an international framework for nuclear disarmament and nonproliferation, recognizes nuclear arms possession by the United States, Russia, Britain, France and China, but obliges the five countries to engage in negotiations on nuclear arms reduction.

If the nuclear powers fail to fulfill their obligations based on the treaty, a trend of disregarding norms could spread, potentially encouraging moves to pursue nuclear possession elsewhere, such as North Korea, which is advancing its nuclear and missile development, and Iran, which is suspected of developing nuclear arms.

Although Japan is under the U.S. nuclear umbrella, its proximity to China, Russia and North Korea leaves it exposed to nuclear threats. Japan must continue to strongly urge the international community to urgently rebuild a framework for nuclear arms reduction.

(From The Yomiuri Shimbun, Feb. 7, 2026)