With Just One Nuclear Arms Treaty Left, a New US-Russia Arms Race Could Be Looming

For decades, the US and the Soviet Union maintained a fragile peace under the looming threat of nuclear war. While the Cuban missile crisis brought the world close to disaster, the Cold War eventually saw arms control agreements aimed at reducing the risk of nuclear conflict.

Starting in the 1970s, both sides began signing agreements to limit and reduce their nuclear arsenals, including the 1987 Intermediate-range Nuclear Forces Treaty (INF), which eliminated a whole class of nuclear missiles.

Russia Ends Moratorium on Deploying IRBMs

But that treaty ended in 2019 after the US withdrew, accusing Russia of violations — a claim Moscow has denied since. This week, the Kremlin announced that Russia would no longer abide by the moratorium (self-imposed limits) on deploying the middle-range IRBMs covered under the INF pact, effectively ending the treaty’s restrictions, as reported by The Associated Press.

Consequently, the latest announcement leaves just one bilateral arms control treaty still in force — the New Strategic Arms Reduction Treaty (New START) signed in 201 that limits deployed nuclear weapons and requires inspections. 

New START is “functionally dead”, Sidharth Kaushal, a senior fellow at the Royal United Services Institute (RUSI), told the US-based news agency as it is “set to expire in February 2026”.

From Thousands to Thousands: How Nuclear Stockpiles Have Changed

At the height of the Cold War in 1986, the Soviet Union had over 40,000 nuclear warheads and the US had over 20,000, the report stated, citing the Federation of American Scientists.

Since then, arms control agreements significantly reduced these numbers. By March 2025, the FAS estimates put Russia’s nuclear arsenal at around 5,459 warheads and the US at 5,177 — together accounting for roughly 87% of the world’s nuclear weapons, according to AP.

However, the risk remains, especially with the collapse of key treaties and the rise of new missile technologies.

Key Treaties and Their Collapse

The earliest milestones that placed limits on missiles and missile defenses were reached through the 1972 Strategic Arms Limitation Talks I (SALT I) and Anti-Ballistic Missile (ABM) Treaty.

The INF Treaty prohibited land-based missiles with 500 to 5,500 kilometers ranges in 1987. The US pulled out in 2019, arguing that Russia had breached the treaty and that the treaty did not mention China and Iran’s missile plans. Although Moscow initially promised that it would abide by the treaty, Moscow ended that this week.

At the same time, President Vladimir Putin announced that Russia’s new intermediate-range hypersonic missile, Oreshnik was test-fired in Ukraine and will be deployed in Belarus this year, also indicating renewed emphasis on missile development.

The 1991 START I treaty further decreased strategic nuclear weapons but has since lapsed. START II was signed but not enforced.

The US withdrew from the ABM Treaty in 2002 following the 9/11 attacks as a necessary measure to protect against possible threats from Iran and North Korea. Russia had opposed the move in strong terms.

What’s Left? New START and Rising Risks

New START is the last remaining bilateral treaty, limiting deployed nuclear warheads and requiring inspections. However, Russia suspended participation after its 2022 invasion of Ukraine with the halting of on-site inspections. Moscow, for its part, has insisted that it will still abide by the treaty’s limits, at least for now.

Alexander Bollfrass from the International Institute for Strategic Studies told AP, “While the end of nuclear weapons agreements between the US and Russia does not necessarily make nuclear war more likely, it certainly doesn’t make it less likely.”

Bollfrass also noted that the INF and New START treaties allowed “serious on-the-ground inspections” that helped lower tensions in Europe, and their absence could increase them.

The Bigger Picture: Other Nuclear Players and Emerging Threats

While a great deal of focus remains on the US and Russia, other countries like China, Israel and Iran are becoming increasingly significant players in missile development and deployment.

Experts have warned that with China’s growing nuclear capabilities, the US may ramp up its own arsenal in response. Kaushal from the RUSI warned this could trigger a “competitive spiral,” with both the US and Russia expanding their nuclear weapons, as reported by The Associated Press.

According to the report, new bilateral nuclear agreements between the US and Russia look “highly unlikely” in the near future, given the lack of trust and the shifting geopolitical landscape.

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