As of February 5, 2026, the New START treaty, the last major arms control deal between the United States and Russia, has expired, leaving no formal limits on the world’s two largest nuclear arsenals. This shift has experts worried that a new nuclear arms race might be beginning.
What Was New START?
New START was signed in 2010 by U.S. President Barack Obama and Russian President Dmitry Medvedev. It limited each country to no more than 1,550 deployed strategic nuclear warheads and 800 delivery systems such as missiles and bombers. The treaty also included inspection and data-sharing measures designed to build trust and transparency between the two powers.
That framework has helped keep nuclear tensions in check for over a decade. But diplomatic relations have chilled in recent years, especially after Russia’s 2022 invasion of Ukraine, and arms control talks have stalled. Even when Russia offered a one-year extension in 2025, the United States did not formally agree to keep it in force.
Why the Expiry Matters
With New START no longer in effect, there are no mutual legal limits on how many nuclear weapons the U.S. and Russia can deploy. Observers say this means both countries could begin expanding their arsenals without restraint. Before the treaty, the world saw stockpiles of tens of thousands of nuclear warheads during the Cold War. New START helped reduce those numbers and kept both sides accountable.
Kremlin officials themselves acknowledge that the world will likely be more dangerous without the treaty, warning that dropping such a fundamental agreement could weaken global security and strategic stability.
Concerns About a New Arms Race
Many arms control experts fear that the lapse could spark a renewed competition to build more powerful or larger nuclear forces. Without agreed limits, each country might feel pressure to respond to the other’s moves, potentially escalating tensions. Some analysts also note that other nuclear powers, like China, are expanding their arsenals, which could further complicate global stability.
Even though Russia has said it will not be pushed into an arms race, its deputy foreign minister noted that ongoing modernization of nuclear forces is already underway.
The end of New START doesn’t automatically mean missiles will start flying, but it removes key guardrails that helped prevent unchecked nuclear competition for more than a decade. Many observers say this change places the world closer to a new, unregulated age of nuclear weapons, one with greater uncertainty and risk than at any time since the end of the Cold War.
