The Last Nuclear Guardrail Just Disappeared

February 4th marked the end of an era. The New START treaty—the last remaining agreement constraining Russian and US nuclear weapons—quietly expired, taking with it the final guardrail preventing a new nuclear arms race.

When asked about the treaty's expiration, Donald Trump was characteristically dismissive: "If it expires, it expires." But behind that casual shrug lies a seismic shift. For the first time since the 1970s, the world's two largest nuclear powers operate without any binding limits on their arsenals.

What We Just Lost

The New START treaty wasn't just about numbers—though those mattered. It capped both nations at 1,550 deployed strategic warheads and 800 delivery vehicles. More crucially, it created a verification system that allowed 18 inspections per year and regular data exchanges about nuclear capabilities.

That transparency is now gone. Neither side knows exactly what the other is building, testing, or deploying. In the nuclear realm, uncertainty breeds paranoia, and paranoia breeds dangerous miscalculations.

Vladimir Putin had already suspended Russia's participation last year, citing Western support for Ukraine as justification. Since then, Russia has unveiled weapons that existing treaties couldn't cover anyway—hypersonic Sarmat missiles, nuclear torpedoes like Poseidon, and other systems designed to evade traditional defenses.

Trump's Nuclear Math

Why isn't the Trump administration rushing to extend the treaty? The answer lies in Beijing. China's nuclear arsenal, estimated at around 350 warheads, is growing rapidly. The Pentagon projects China could have 1,000+ warheads by 2030—a three-fold increase that would fundamentally alter the nuclear balance.

The problem: China refuses to join arms control talks. Beijing argues its arsenal is still much smaller than the US or Russia's, so why should it accept limits? Trump's position is simple: "No deal without China at the table."

This logic has merit, but it also has flaws. Using China's non-participation to justify abandoning existing constraints might be throwing away the good in pursuit of the perfect. Critics argue it's really about creating political cover for a military buildup that was already planned.

The Domino Effect

The treaty's expiration sends ripples far beyond Washington and Moscow. Other nations are watching closely. If the superpowers can't maintain basic nuclear discipline, why should anyone else show restraint?

North Korea has already demonstrated this logic, building an estimated 90 warheads while the world focused elsewhere. With the US-Russia framework collapsing, Pyongyang faces even less international pressure to limit its program.

Meanwhile, countries like Saudi Arabia and Turkey have begun making noises about their own nuclear options. The nuclear domino theory that kept policymakers awake during the Cold War is looking less theoretical by the day.

What Comes Next

Without treaty constraints, both sides will likely begin expanding their arsenals. Russia is already developing new weapons systems, while the US plans to spend $1.7 trillion over 30 years modernizing its nuclear forces. That's before any new arms race really begins.

The real danger isn't just more weapons—it's less predictability. Arms control treaties serve as communication channels, reducing the risk of misunderstandings during crises. When those channels disappear, so does the ability to signal intentions clearly.

Allies are already nervous. European NATO members worry about extended deterrence commitments, while Asian allies question whether America can simultaneously deter China, Russia, and North Korea. The answer may depend on how willing Americans are to pay for a much larger nuclear force.