Just days before it was due to expire, the United States and Russia extended the New START treaty—the only major arms control agreement left between the two powers. Its expiration would have marked the first time since 1972 that the nuclear arsenals of Washington and Moscow were not subject to some form of agreed limitations. The five-year extension, however, is a one-time event. U.S. President Joe Biden now faces the question of what should come next.
The welcome extension of New START comes at a worrying moment. Although the United States and Russia have nowhere near the number of nuclear weapons they possessed at the height of the Cold War, both countries are again in the midst of an arms race. Over the past decade, each side has developed new missiles, bombers, submarines, and capabilities to shoot down satellites. Other countries, including China and even North Korea, are warming up, too.
This renewed competition traces its origins to 2001. In the wake of the September 11 terrorist attacks, U.S. President George W. Bush announced that Washington would withdraw from the 1972 treaty limiting missile defenses, a step he argued was necessary to defend the United States against a rogue nuclear strike. In the years that followed, Russia and China responded with campaigns to modernize their nuclear arsenals, fearing that new American capabilities would leave them vulnerable in ways that Washington could exploit.
If Biden wants to slow this arms race, he will need to accept limits on the U.S. missile defense