UN Secretary-General Antonio Guterres on Wednesday described the expiration of the New START Treaty as a serious threat to global peace and security, calling on Russia and the United States to quickly begin talks on a new nuclear arms control agreement. The treaty, which expired at midnight, had placed limits on the number of strategic nuclear warheads and delivery systems—such as land- and submarine-based missiles and bombers—that both countries could deploy.

Guterres warned that, for the first time in over 50 years, there are no legally binding restrictions on the nuclear arsenals of the two nations that hold most of the world’s nuclear weapons. He stressed that the collapse of decades of arms control efforts comes at an especially dangerous time, with the risk of nuclear weapon use at its highest in decades.

Despite the risks, he said the moment also offers a chance to rebuild and design a modern arms control system suited to today’s rapidly changing global environment. Guterres welcomed signals from both Moscow and Washington acknowledging the need to avoid unchecked nuclear proliferation. Emphasizing the need for action, he urged both countries to move beyond statements and immediately resume negotiations to establish a successor framework that reinstates verifiable limits, lowers risks, and enhances shared global security.