On Feb. 5, 2026, nearly half a century of bilateral arms control treaties between the United States and Russia ended when New START expired, with no replacement in place. Signed by presidents Barack Obama and Dmitri Medvedev in 2010, New START entered into force in February 2011 as the successor to the 1991 Strategic Arms Reduction Treaty, the first major attempt by the United States and Soviet Union to decrease their strategic nuclear arsenals.
Under New START, the U.S. and Russia were each obligated to maintain the central limits on strategic offensive weapons: 700 deployed missiles and heavy bombers, 800 deployed and non-deployed missile and bomber launchers, and 1,550 nuclear warheads on deployed arms. In addition, New START granted both U.S. and Russian officials unprecedented access to each other’s nuclear facilities to conduct inspections.
In 2025, Russian President Vladimir Putin proposed unofficially observing the terms of the agreement for an extra year past the expiration date until a new agreement could be drawn. U.S. President Donald Trump declined, stating that “if it expires, it expires… we’ll do a better agreement.” Without a successor agreement or a formal return to compliance, 2026 could mark the first time in decades that the U.S. and Russia have no legal constraints on their nuclear arsenals. Here is what’s Good to Know about the end of New START.
What is New START?
When Russia and the U.S. signed New START in 2010, it was a commitment to build upon the highly successful nuclear disarmament regime that emerged at the end of the Cold War. The first of the START treaties, signed in 1991, was a landmark agreement that transitioned the two superpowers from merely capping their nuclear arsenals to actively dismantling them. It was the largest and most complex arms control treaty in history, limiting both sides to 6,000 “accountable” warheads and 1,600 delivery vehicles (missiles and bombers). Following the collapse of the Soviet Union in late 1991, the treaty was saved by the Lisbon Protocol, which ensured that the newly independent states of Belarus, Kazakhstan, and Ukraine would transfer their nuclear weapons to Russia or destroy them.
In 1993, the U.S. and Russia attempted to build on this momentum with START II, a treaty that holds the dubious distinction of being ratified by both countries, but never successfully implemented. START II sought to draw down arsenals even further, lowering both sides to just 3,000 strategic weapons. More significantly, this treaty promised a ban on MIRVs (multiple independent re-entry vehicles). Because these weapons contained multiple warheads on a single missile, they posed a unique offensive threat to the other side’s arsenal. And if either side believed that their arsenals could be wiped out with MIRVs, they would be tempted to “use or lose” their nuclear weapons during a crisis.
With tensions rising over NATO expansion and President George W. Bush’s withdrawal from the Anti-Ballistic Missile Treaty in 2002, Russia declared START II null and void. START I remained in effect until its expiration in 2009 – and successfully led to the removal of roughly 80% of all strategic nuclear weapons then in existence. New START took these reductions further, in what many U.S. analysts saw as a critical part of the broader “Russian reset” strategy, as the Obama administration attempted to build a more cooperative relationship with Russia.
The impact of arms control
Arms control proponents hail the START treaties as critical for maintaining stability between the two largest nuclear powers. These treaties, including New START, had two primary impacts on nuclear relations between the U.S. and Russia: creating a strategic balance between the two nuclear superpowers and establishing inspection systems that enable mutual transparency and predictability.
From the beginning, START treaties were designed to limit what many experts saw as dangerous and unnecessary arms racing between the superpowers. Quantitatively, when START negotiations began, the U.S. and the Soviet Union each had over 10,000 warheads and launchers. Qualitatively, each side sought a “first strike” capacity, investing in MIRVs and surveillance technology to enable preemptive, offensive action against rival arsenals. START sought to put limits on both the quantitative and qualitative arms race.
Second, the START treaties contained provisions that provided both the U.S. and Russia with reliable and verifiable insights into each other’s nuclear weapons capability. Each country was granted 18 on-site inspections a year, designed to allow access to verify the size and composition of each side’s strategic arsenal – an example of President Ronald Reagan’s “trust, but verify” approach to disarmament. “The transparency and balance created by New START were critical in preventing arms racing between the U.S. and Russia, lowering the overall risk of misconstruing conventional military activity and weapons movement as nuclear mobilization.
To be clear, even supporters recognized it was not a faultless treaty. While New START provided stricter numerical limits than previous treaties, the treaty was limited to preventing the deployment of strategic weapons, thereby ignoring Russia’s regional weapons designed for tactical use. Newer technologies, including hypersonic, undersea, and space weapons, are also not covered by New START. Putin’s 2023 suspension of New START in response to the war in Ukraine led to a pause in inspections for both sides, further worsening tensions between Russia and the United States.
What’s next?
Despite Trump’s promise to seek a better nuclear deal, several obstacles threaten efforts to revive the START regime. Most obviously, relations with Russia have worsened considerably since 2009, and the war in Ukraine and Putin’s 2023 suspension of New START have further damaged the possibility of talks. Russia has relied on nuclear posturing as a means of maintaining deterrence in the face of a combined U.S./NATO conventional arsenal that’s superior to its own arsenal. In this light, Russia has threatened tactical nuclear use both in Ukraine and against nuclear-armed countries offering assistance to Ukraine, such as the U.S., U.K., and France. It is unclear how successful any arms treaty would be, at least for the duration of the war in Ukraine – the Kremlin’s reliance on a first-use policy and frequent signaling are critical components of its deterrent strategy.
The rise of newer nuclear powers has further complicated matters. At the time of the START and New START negotiations, China was not a significant nuclear power. For decades, China opted to maintain a small deterrent capability rather than a massive nuclear arsenal. Over the last decade, however, China has rapidly modernized its nuclear capacity, which is now slated to mirror that of the U.S. by 2035. While Trump has expressed a desire to involve China in a new arms control treaty, China has historically been reticent about entering into these negotiations. China points out it maintains a no-first-use policy, and reiterates the asymmetrical force structure between three nuclear powers.
A final, important note is that Russia, China, and the U.S. are all engaged in a massive modernization of their strategic arsenals. The United States is currently overhauling its entire “Triad,” replacing an aging ICBM force, launching the Columbia-class submarine program, and deploying the B-21 Raider stealth bomber. The U.S. has also invested in low-yield precision nuclear weapons to strengthen the credibility of its deterrence. Meanwhile, Russia has largely completed its modernization cycle, including the Avangard hypersonic glide vehicle, specifically designed to bypass Western missile defenses. By 2030, China plans to have a functional “nuclear triad,” and over 1,000 deployed strategic weapons. Given that all of these countries are seeking a qualitative leap forward, they may be unwilling to sign on to a treaty that requires them to cede any weapons advantage.
To put it mildly, then, a new comprehensive treaty might be possible, but would certainly face unprecedented challenges. Any negotiations would have to account not just for strategic capabilities but tactical ones. Any new agreement would also have to address new technological advancements. And negotiations would involve a multilateral effort, not just the United States and Russia. Given China’s reticence to participate, ongoing Russian efforts in Ukraine, and Trump’s own vacillations, a renewed and strengthened START regime seems unlikely for now.
Ananya Balakrishnan is a senior at Wellesley College, double-majoring in international relations-political science and peace and justice studies. She is a co-founder and project director of the Security Studies Lab, a student-led research lab centering on international security questions. Her research examines networked nuclear assistance dynamics, the non-proliferation regime, and security assistance to proxy groups. She was a 2026 fellow at the Madeleine K. Albright Institute for Global Affairs.
Maria C. Garcia is a senior at Wellesley College, majoring in political science alongside a minor in Middle Eastern studies. She is a co-founder and project director of the Security Studies Lab, engaging in research which explores the question of which logics are the true drivers of sustained non-use in an ever-developing nuclear weapons landscape.
Stacie E. Goddard is Betty Freyhof Johnson ’44 Professor of Political Science and Paula Phillips Bernstein ’58 Faculty Director of the Madeleine K. Albright Institute for Global Affairs at Wellesley College. Her research focuses on issues of international security, especially great power competition and its effects on international institutions. She is the author of When Right Makes Might: Rising Powers and World Order (Cornell University Press, 2018).
