Last US-Russia Nuclear Treaty Expires, Leaving World Without Key Safeguard Against Arms Race

The last surviving US-Russia nuclear treaty is set to expire tomorrow, February 5, 2025, leaving the world without a critical safeguard against an escalating arms race. The New Strategic Arms Reduction Treaty (New START), signed in 2010, has served as a cornerstone of nuclear restraint for over a decade. Its expiration marks the first time since the Cold War that the United States and Russia will operate without formal limits on their strategic nuclear arsenals, a development that experts warn could reignite a dangerous global competition.

New START limited each nation to 1,550 deployed strategic warheads, providing a mechanism for verification and maintaining a balance of power between the world's two largest nuclear arsenals. Dr. Jim Walsh, a senior research associate at MIT's Security Studies Program, warned that while the treaty's expiration won't immediately dismantle nuclear restraint, it sets the stage for a potential chain reaction. 'There'll be a turn of events a month from now, a year from now, five years from now,' Walsh said. 'Things always happen in international affairs. There'll be a war, there'll be a crisis.'

The absence of New START removes the last numerical checks on US and Russian nuclear forces, a situation not seen since the height of the Cold War. Experts argue that even a single regional conflict could prompt rapid nuclear expansion, as nations race to rebuild their arsenals in anticipation of future threats. 'Once these restraints are gone, escalation can happen rapidly,' Walsh explained. 'Momentum builds, and countries move before they have time to reconsider.'

President Donald Trump, who was reelected in January 2025, has signaled he will allow the treaty to expire without accepting Moscow's proposal to voluntarily maintain its nuclear limits. 'If it expires, it expires,' Trump told the *New York Times*. 'We'll just do a better agreement.' However, arms control experts argue that such a move removes the last remaining checks on nuclear proliferation. John Erath, a senior policy director at the Center for Arms Control and Non-Proliferation, criticized the failure of US leaders to prepare a successor agreement. 'The expiration of the treaty is a symptom, not the disease,' Erath said. 'There's a lot going on that's increasing the perception that nuclear war is possible.'

The absence of formal restraints has already sparked warnings about the erosion of global stability. Russia currently possesses the largest confirmed nuclear arsenal, with over 5,500 warheads, while the United States holds approximately 5,044. Together, the two nations account for nearly 90 percent of the world's nuclear weapons. A nuclear strike from Russia could reach the continental United States in 30 minutes via intercontinental ballistic missile (ICBM), a chilling reminder of the speed at which destruction could unfold.

Walsh highlighted past US withdrawals from arms control agreements as cautionary examples. The George W. Bush administration's exit from the Anti-Ballistic Missile Treaty, for instance, is now linked to China's accelerated nuclear modernization. 'We've built missile defenses, which are a direct threat to their nuclear deterrent,' Walsh said. Similarly, the US withdrawal from the Iran nuclear deal has led to Iran's pursuit of nuclear capabilities, despite its previous compliance with the agreement.

Despite efforts by Russian President Vladimir Putin to extend the treaty for another 12 months, the treaty was structured to allow only a single extension—which was already used under the Biden administration. 'You can't force someone to negotiate,' Walsh emphasized. 'A negotiation is a voluntary activity.' He warned that without the shared sense of urgency that characterized past arms control breakthroughs, the world is drifting toward a more unstable and precarious future.

As global institutions weaken and nationalism rises, the risk of miscalculation grows. Erath called for 'leadership and political will' to prevent the situation from spiraling out of control. 'What's needed is not just a treaty, but a renewed commitment to the institutions that keep the world from falling into chaos,' he said. With the last nuclear safeguard gone, the world now faces a reckoning—one that could reshape the balance of power, redefine global security, and test humanity's ability to avoid the brink of annihilation.