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On February 5, 2026, the last treaty constraining the nuclear arsenals of the world’s two largest nuclear powers expired at midnight. For the first time since the early 1970s, the United States and Russia now operate without any enforceable caps on their most powerful nuclear weapons designed to destroy entire cities—no cap on deployed warheads, no ways to check and verify what the other side is doing with its most destructive weapons.
The New Strategic Arms Reduction Treaty, which had limited each nation to 1,550 nuclear weapons ready to launch right now since 2011, is gone. What remains is uncertainty about whether a new arms race will follow, what the risk of nuclear miscalculation looks like without ways to check and verify what the other side is doing, and whether the world has entered a more dangerous nuclear era.
Russia proposed a one-year extension of the core numerical limits. The White House gambled that refusing to extend would create pressure for a “better” agreement—one that would include China.
What Disappeared
New START did two things that mattered. First, it capped deployed strategic warheads at 1,550 per side and limited deployed delivery systems—ways to deliver them: long-range missiles, missiles from submarines, and bombers—to 700. Second, it created an inspection system that allowed up to eighteen on-site inspections annually, twice-yearly reports on where weapons were and what they could do, and notification before major missile tests.
American inspectors had the right to conduct short-notice inspections at Russian nuclear facilities and directly count warheads on deployed missiles, with inspections typically occurring within a matter of days following notification. Russia had the same access to U.S. facilities.
Without that access, U.S. military planners have to rely on satellite surveillance and intercepted communications and electronic signals—less reliable and easier to misread or get wrong, more likely to generate assumptions that the other side has more weapons than it probably does.
The Slow Collapse
New START didn’t die suddenly. It deteriorated.
COVID-19 halted inspections in 2020. Then Russia invaded Ukraine in February 2022, and the agreement came under acute strain. By February 2023, Putin officially pulled out and refused to allow inspections, rejecting inspections and refusing data exchanges. The U.S. responded by suspending its own data sharing and revoking visas for Russian inspectors.
For the final three years, the verification system that made it meaningful simply didn’t function. The numerical limits technically remained in force, but neither side could verify the other’s compliance.
Yet even in this degraded state, New START mattered. The limits still forced both sides to think carefully about their options. Both sides maintained rough compliance with the 1,550 warhead limit, not because they had to legally, but because the structure created expectations.
The China Gambit
Trump initially seemed interested in a one-year extension. Then something shifted. By January 2026, Trump told The New York Times that if New START expired, “it expires,” and that he would seek “a better agreement” that included China.
China’s nuclear arsenal has grown substantially at a breathtaking pace of expansion. But Beijing has consistently and explicitly refused to participate in arms control negotiations. China says the U.S. and Russia should reduce their arsenals first. Only once U.S. and Russian arsenals approach Chinese levels would Beijing consider joining restrictions. Joining trilateral negotiations now would permanently accept having fewer weapons than the U.S. and Russia. Any agreement imposing caps based on current levels would formalize that inferiority and prevent China from building toward parity.
The administration’s bet is that maintaining pressure will somehow force Beijing’s hand. The problem is that abandoning existing constraints in pursuit of a future trilateral arrangement is particularly risky when the interim period involves no caps whatsoever.
What Changes
The immediate consequence is that both nations can now move more warheads from storage into weapons that are ready to launch relatively rapidly. With the weapons they already have stored, the U.S. and Russia could activate hundreds of additional warheads in a relatively short timeframe—though the exact speed depends on technical and logistical factors including warhead readiness, delivery system availability, and maintenance requirements. The process involves uploading reserve warheads onto existing delivery systems that currently carry fewer warheads than their maximum capacity.
Moscow has been maintaining production capacity in its nuclear weapons infrastructure despite earlier caps.
More concerning than the numbers is the loss of transparency. No more U.S. or Russian inspectors visiting nuclear weapons facilities. No more data exchanges on warhead numbers or launcher locations. No more notifications before major missile tests. When transparency collapses, nuclear-armed states assume the worst. Military planners on both sides must now make assumptions instead of relying on direct observation. When assumptions are uncertain, the tendency is to assume the worst—to build forces to counter the maximum threat the adversary might pose rather than the threat it poses. This creates a dangerous pattern where each side builds more weapons because it fears the other.
Some defense analysts argue that modern satellite surveillance provides sufficient monitoring capability. The National Reconnaissance Office operates sophisticated satellite systems that can monitor Russian nuclear facilities. But even advocates for this view acknowledge trade-offs. The loss of direct access means less detailed knowledge, not merely slightly reduced certainty.
The Timing Problem
The expiration comes at an exceptionally bad moment. The U.S. and Russia are engaged in a proxy war in Ukraine. NATO and Moscow face each other across an active conflict zone. China is assertively expanding its capabilities in the Indo-Pacific. Tensions among all three major powers are elevated.
Moscow has repeatedly suggested it might use nuclear weapons in Ukraine as a tool of coercion against the United States and European countries. Whether Putin would order nuclear use remains deeply uncertain, but the threats themselves create danger.
When Moscow announces nuclear maneuvers or conducts strategic exercises, is it real military moves or just trying to scare people? In the absence of inspections and data exchanges, uncertainty increases. During the Cold War, arms control agreements were negotiated during periods of tension precisely because both sides recognized that some way to reduce the danger was preferable to unlimited competition.
Negotiating new agreements takes time. The interim period is more dangerous.
The Allied Problem
New START’s expiration has worried America’s allies—particularly those on NATO’s eastern flank. They depend on the U.S. nuclear umbrella—America’s promise to use nuclear weapons to protect its allies against Russia. For decades, the arms control agreement proved the U.S. was serious about protecting allies by demonstrating that the U.S. maintained capabilities while accepting mutual vulnerability for the sake of negotiated caps. The collapse of New START creates questions about how the U.S. will structure its deterrent in the future.
More countries are seriously considering getting nuclear weapons—places like Japan, Poland, South Korea, and Turkey. Japan has been discussing what expanded nuclear deterrent roles it might play absent clear U.S. protection. Poland has been discussing acquiring nuclear weapons. South Korea and Taiwan face direct threats from nuclear-armed adversaries and have periodically discussed independent capability.
The more nations that acquire or expand nuclear capability, the greater the risk of accident, miscalculation, or war between nuclear-armed adversaries. The Non-Proliferation Treaty made a bargain in 1968: nuclear powers promised to reduce weapons while other countries promised not to build them. When nuclear-armed states abandon arms control agreements, it undermines the credibility of that deal.
The disappearance of the last U.S.-Russia agreement in the absence of a replacement signals that nuclear powers are abandoning restraint. This could be particularly damaging at the NPT Review Conference scheduled for April-May 2026, where non-nuclear states are likely to express deep frustration with the collapse of arms control between the superpowers.
The Modernization Machine
Both the U.S. and Russia face aging nuclear arsenals requiring modernization regardless of whether caps exist. Tom Morrison, deputy assistant to the president for national security in the first administration, testified to Congress that “by 2035, all U.S. nuclear weapons will be older than they were built to last by an average of 30 years.”
The administration has accelerated spending on nuclear modernization dramatically. The fiscal year 2026 budget request included $62 billion for nuclear forces, a 26 percent increase over the previous year. The budget included funding for the Sentinel ICBM program, Columbia-class ballistic missile submarines, B-21 stealth bombers, and a nuclear-capable sea-launched cruise missile. The Congressional Budget Office estimated that the overall cost of modernizing and maintaining the U.S. nuclear enterprise will be $946 billion from 2025 through 2034.
New START’s expiration might slow rather than accelerate U.S. buildup, at least in the near term. These modernization programs were already planned and funded. The expiration doesn’t force the U.S. to build faster or build more. What it does is remove the rule that limited how many weapons could be active—the assumption that deployed numbers should not exceed 1,550 warheads.
If the Pentagon decides that deterrence against both adversaries requires more than 1,550 nuclear weapons ready to launch right now, it can now recommend increasing that number. But deploying those warheads would require the weapons to be built, tested, and deployed operationally. All of which takes time and resources.
Moscow faces similar pressures. The Russian nuclear weapons complex has been actively maintaining production capacity. Recent deployments of new systems—the Poseidon underwater drone, the Burevestnik cruise missile—demonstrate an active modernization program. Like the U.S., Russia can conduct this modernization regardless of whether caps exist. The difference is that in the absence of New START’s constraint, Russia doesn’t have to take old weapons out of service when it puts new ones in. It can keep both in service, potentially ending up with more weapons total instead of just swapping old for new.
What Might Come Next
Even as New START expired, unofficial discussions about what might replace it were underway. Axios reported that U.S. and Russian officials were close to agreeing to follow some of the old rules in the final days before expiration, though without making it an official law.
Some observers suggested the White House might revive a proposal for a one-year informal extension of the numerical caps, even in the absence of verification mechanisms. Such an arrangement would not have legal force, but both sides might agree to it as a way to build trust while they kept talking.
Alternatively, the administration could pursue what it has described as a more ambitious agreement including China. A three-way nuclear deal would be extraordinarily ambitious—the hardest arms control negotiation ever attempted, requiring agreement among three countries with different goals and different plans for using nuclear weapons. The U.S. and Russia have spent decades developing definitions and rules that both find acceptable. Doing this trilaterally with China would be vastly more difficult, particularly when Beijing has explicitly rejected participation.
A middle path would involve extending bilateral caps while simultaneously quietly talking to China about how to avoid nuclear accidents—measures that don’t create binding rules but reduce the risk of miscalculation. This might include establishing military-to-military communication channels specifically focused on nuclear issues, agreements to warn each other before nuclear weapons exercises, and agreements on how to talk to each other during emergencies. Beijing has refused to even discuss these informal measures, but the collapse of U.S.-Russia arms control might give China reasons to at least discuss crisis management.
The Risk
If Russia quickly activates more weapons and the U.S. does the same, both sides could start building weapons as fast as possible. That would increase the risk of miscalculation and situations where fear of attack pushes countries to launch weapons first. If both sides exercise restraint while pursuing new negotiations, a new agreement might eventually be reached. Or something in between might happen—informal deals might keep loose limits on weapons while negotiations drag on and stop and start for years.
The risk of nuclear use is higher now because verification mechanisms that reduced miscalculation are gone. The prospect of a new arms race is higher because there are no caps. The possibility of proliferation is higher because the Non-Proliferation Treaty depends on the big powers demonstrating restraint.
Nuclear war remains unlikely. Both the U.S. and Russia understand that nuclear use would be catastrophic. The loss of New START doesn’t change that fundamental calculation.
What it does change is the margin for error. Without verification, countries have to guess instead of knowing. Without caps, countries don’t have to hold back. Without rules, countries can do whatever they want. Each of these changes makes nuclear war slightly more likely, slightly more likely to lead to accidents or misunderstandings, slightly more dangerous.
How much more dangerous depends on decisions that haven’t been made yet by the administration, the Russian government, the Chinese government, and the international community.
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