After New START: The Treaty That Ended in February 2026 and What Comes Next

February 5, 2026 was a Thursday, and nothing exploded. No missiles were moved that anyone announced, no alarms sounded, and most Americans had no idea that a line had been crossed. But for the first time since the early 1970s, with a short gap here and there, no treaty was in force limiting the long-range nuclear arsenals of the United States and Russia. New START, signed in Prague in 2010 and extended once in 2021, had run out the clock on its final term. The end of an arms-control treaty is not a dramatic event. It is the quiet removal of a guardrail on a road most people never look at, and the danger shows up only later, if at all.

In short: New START capped deployed US and Russian strategic warheads at 1,550 each and gave both sides on-site inspections, until Russia suspended its participation in 2023 and the treaty's last term ended in February 2026. This explainer walks through fifty years of US-Russian arms limits, how verification worked, why the system fell apart, and the realistic options for building something new, including bringing China into the conversation.

What New START actually limited

The treaty's name stood for Strategic Arms Reduction Treaty, with "New" added because there had been an earlier one. Presidents Barack Obama and Dmitry Medvedev signed it on April 8, 2010, and the Senate approved it that December by a vote of 71 to 26, with thirteen Republicans joining Democrats. It entered into force on February 5, 2011.

Its central limits were simple to state:

• No more than 1,550 deployed strategic warheads for each side.
• No more than 700 deployed intercontinental ballistic missiles, submarine-launched ballistic missiles and heavy bombers equipped for nuclear arms.
• No more than 800 deployed and non-deployed launchers of those kinds.

"Strategic" means the long-range weapons each country could use against the other's homeland. The treaty did not cover shorter-range "tactical" nuclear weapons, where Russia holds a larger stockpile, which was one of the main objections raised by its critics.

The treaty ran for ten years with an option to extend for up to five more. In early 2021, days after President Biden took office, the two governments agreed to the full five-year extension, which set the final end date at February 5, 2026. The treaty contained no provision for a second extension.

The part that mattered most: looking inside

Numbers on paper are only as good as the ability to check them, and New START's real value lay in verification. Each side could carry out up to eighteen on-site inspections a year at the other's bases, where inspectors could, for example, count the warheads on a particular missile. The two countries exchanged data on their forces twice a year and sent each other notifications whenever weapons moved or changed status, which over the life of the treaty added up to many thousands of messages.

That flow of information did something beyond counting. It gave military planners on each side a reasonably accurate picture of the other's forces, which lowered the pressure to plan for the worst case. A planner who does not know what the other side has tends to assume it has more, and then asks for more to match it. Verification is a brake on that spiral.

Inspections stopped in 2020 because of the pandemic. They never fully resumed. In February 2023, Vladimir Putin announced that Russia was suspending its participation in the treaty, citing American support for Ukraine. Russia said it would keep to the central limits, but data exchanges and inspections ended. The United States, in turn, stopped sharing some of its own data. For its last three years New START was a set of numbers each side said it respected and neither could confirm.

Half a century of limits, in brief

New START was the last in a long line. Knowing the line helps make sense of what has been lost.

SALT I (1972). Richard Nixon and Leonid Brezhnev signed an interim agreement freezing the number of ballistic missile launchers, alongside the Anti-Ballistic Missile Treaty, which sharply limited missile defences on the theory that if neither side could shield itself, neither would be tempted to strike first.

SALT II (1979). Signed by Jimmy Carter and Brezhnev, it was withdrawn from Senate consideration after the Soviet invasion of Afghanistan. Both sides said for a time that they would observe it anyway.

INF (1987). Ronald Reagan and Mikhail Gorbachev eliminated a whole class of intermediate-range missiles, with on-site inspections. The United States withdrew in 2019, accusing Russia of violations.

START I (1991). Signed by George H. W. Bush and Gorbachev just months before the Soviet Union dissolved, it made deep cuts and created the detailed verification system on which New START later drew.

The 2000s. START II was signed but never entered into force. The United States withdrew from the ABM Treaty in 2002, arguing that it needed defences against smaller states. The 2002 Moscow Treaty set lower warhead limits but had no verification of its own.

Across that history, arsenals fell from the tens of thousands of warheads at the height of the Cold War to a small fraction of that. Republicans and Democrats both signed these agreements. It was, for decades, one of the few areas of real bipartisan continuity in foreign policy.

Why the system broke down

The collapse has several causes, and an honest account should name them all.

Russia's full-scale invasion of Ukraine in 2022 poisoned relations and led to Moscow's suspension of the treaty in 2023. Russian officials also linked arms control to Western military support for Kyiv, which made progress hostage to a war.

American withdrawals from the ABM Treaty in 2002 and the INF Treaty in 2019 had already weakened the structure. Supporters of those decisions argued that the ABM Treaty prevented defence against new threats and that the INF Treaty bound only the United States while Russia cheated and China, never a party, built hundreds of intermediate-range missiles. Critics answered that leaving treaties gave up verification and a forum for complaints without solving the underlying problem.

Then there is China, which has expanded its nuclear arsenal quickly, according to the Pentagon's own annual reports to Congress. China has never been part of any of these treaties and has long said it would not join talks until the much larger American and Russian arsenals came down. Many American defence planners now argue that any new treaty must account for two nuclear rivals at once, which makes the old two-party model look obsolete.

In September 2025 Putin offered to keep observing New START's central numerical limits for one year after it ended, if the United States did the same. President Trump responded publicly that it sounded like a good idea. Whether that kind of informal pledge holds, and for how long, is exactly the problem: an informal pledge has no inspectors.

Weighing the options

What should come next? Here are the realistic paths, with the case for and against each.

Informal mutual restraint. Both sides announce they will stay under the old limits. This is the cheapest and fastest option, and it buys time. Its weakness is that without data exchanges or inspections, each side will eventually suspect the other, and planners will hedge.

A new bilateral treaty. Washington and Moscow negotiate a successor, perhaps covering tactical weapons as well as strategic ones, which American critics of New START always wanted. This is the gold standard, but it would need a two-thirds vote in the Senate and a degree of trust that the war in Ukraine has destroyed.

Bringing in China. A three-way framework is the long-term answer many experts favour, but China's arsenal remains smaller and Beijing has shown little interest. A more modest start might be talks on risk reduction, such as notifications of missile launches or rules for military incidents, rather than numerical limits.

No limits at all. Some argue the treaty era is over and the United States should build up to face two competitors. The case is that deterrence requires matching numbers. The answer, I think, is that an open-ended three-way race would be enormously expensive, would make every crisis more dangerous, and would deliver less security per dollar than almost any other choice. The arms racing of the 1960s and 1970s ended in treaties because both sides found it ruinous, and it would be a strange lesson to relearn.

The bill for an arms race, already arriving

Even before New START ended, the United States had committed to replacing nearly every piece of its nuclear arsenal at once: new submarines, a new bomber, a new land-based missile and new warheads to go with them. Every president since Obama has supported some version of that plan, and the Senate's approval of New START in 2010 was itself tied to promises of modernisation funding.

The costs are large and climbing. The Congressional Budget Office, Congress's nonpartisan scorekeeper, has estimated nuclear forces will cost the country hundreds of billions of dollars a decade. The new land-based missile, called Sentinel, ran so far over its estimates that it triggered a legally required review under the Nunn-McCurdy law in 2024; the Pentagon decided to continue the program anyway while restructuring it.

Here is why that matters to arms control. With a treaty in place, both sides plan against known numbers. Without one, every budget fight comes with a new argument for more: more warheads uploaded onto existing missiles, more submarines, more launchers. Each step can be justified by pointing to the other side's possible steps. The treaty did not just limit weapons; it limited arguments for buying them.

Supporters of the full modernisation plan argue that the existing systems are decades old and that a credible deterrent requires reliable weapons, treaty or no treaty. That is a fair point about replacing old equipment. It is a different question from whether to build beyond the old limits, and voters should insist on keeping the two separate.

The people who did the inspecting

One small, human detail of the treaty years is worth remembering. Under New START and its predecessors, American and Russian military officers spent years visiting each other's bases, sharing meals, counting warheads together and arguing politely over procedures. Some of them got to know each other well. Retired inspectors from both countries have described those relationships as one of the treaty's hidden benefits: a channel of personal trust between militaries that otherwise saw each other only as targets.

That channel is gone for now. Rebuilding it will take more than a signature. It will take years of officers doing tedious, careful work together again, which is exactly what made the old system worth having.

What Congress can and cannot do

Treaties are negotiated by the president, but Congress has real levers. The Senate must approve any new treaty by a two-thirds vote. Congress writes the defence budget, including the hundreds of billions planned for modernising American bombers, submarines and land-based missiles, and can attach conditions to that money. It can also hold hearings that force the administration to explain its plan.

When Democrats take control of the House and Senate in January 2027, after their victories on November 3, 2026, arms control will compete with many other priorities. Whether it gets attention will depend partly on whether voters ask about it. The 2010 vote is a reminder that this used to be bipartisan territory: senators of both parties voted for New START, just as they had for the treaties signed by Republican presidents before it.

Keeping perspective

It is easy to write about arms control as if the world ends when a treaty does. It does not. The United States and the Soviet Union went years without some of these agreements during the Cold War, and deterrence held. But "deterrence held" is a statement about the past, not a guarantee about the future, and the periods without limits were also periods of near misses and runaway spending.

The people most affected by these choices are rarely in the room. They include the communities near missile fields in Montana, North Dakota and Wyoming, the downwinders of past tests in Nevada and New Mexico, and taxpayers everywhere. They also include ordinary Russians and Chinese, who have no more desire for a nuclear war than Americans do. Arms control is, at bottom, an agreement among governments to stop treating their own and each other's citizens as acceptable risks.

What you can do

The end of New START happened quietly. Its successor will only come with noise. Some ways to add yours:

• Ask a precise question. Find your House member and senators on our representatives page and ask whether they support negotiating a verifiable successor to New START and talks with China on nuclear risk reduction.
• Watch the defence bill. The annual defence authorisation and nuclear modernisation spending show up in Congress's votes and bills. Amendments on arms control often get recorded votes, and they tell you where your members stand.
• Read the market as a forecast, not a fact. Our predictions page shows what prediction markets expect on some international questions. Treat those prices as one view of the odds, not a verdict.
• Keep up with the issue. The Pentagon and militarism topic page follows arms control, nuclear spending and the Senate's role in treaties.

A treaty ending without a ceremony is the most natural thing in the world. Getting the next one will take people who noticed.