The nuclear arms control system that helped keep the Cold War from turning hot is slipping. The last major U.S. Russia nuclear treaty, New START, expired on February 5, leaving the two largest nuclear powers in uncharted waters without formal limits. At the same time, China’s nuclear buildup is accelerating fast enough that experts describe it as a storm on the horizon.

The result is a tense triangle: U.S. Russia rules are gone, China is growing quickly, and the prospects for meaningful trilateral talks remain uncertain.

The U.S. and Russia Are Now Unbound

New START had restricted the United States and Russia to 1,550 deployed nuclear warheads each. With the treaty’s expiration, there is now no treaty limiting the world’s most destructive weapons. U.S. officials argue the old framework no longer fits today’s reality.

At a disarmament meeting in Geneva, U.S. assistant secretary of state Christopher Yeaw said New START had been “seriously flawed” and “did not account for the unprecedented, deliberate, rapid and opaque nuclear weapons buildup by China.” He also said New START’s limits on warheads and launchers were “no longer relevant,” citing alleged Russian violations.

Even so, some voices on both sides hint at a path back to talks. Former senior U.S. arms control diplomat Rose Gottemoeller says President Trump has endorsed keeping U.S. nuclear experts engaged with Russian counterparts. From Moscow, Igor Korotchenko, editor of the National Defense Magazine, says Russia is ready to resume talks in the old format or “to find some formula for extending the New START limits.”

But the obstacles are real. Korotchenko says Russia’s main concern is President Trump’s desire to build a “Golden Dome” anti missile shield, which he argues would undermine Russia’s deterrent and make arms control obsolete. That is the core tension: one side wants defense systems it sees as protection, the other sees them as treaty killers.

As treaty limits fade, experts warn of an action reaction cycle. Tong Zhao of Carnegie China says one reason the Trump administration declined to extend New START was to gain leeway to respond to China’s rapid expansion, because Washington “feels the need to react.”

Zhao also predicts a concrete shift on the U.S. side: “We are likely to see the U.S. starting to upload more warheads to missiles,” adding that this “action reaction dynamic” will have broader global implications.

Meanwhile, the U.S. position is that it is not abandoning arms control altogether. Yeaw said the U.S. is not “walking away from or ignoring arms control,” and argued, “Our goal, is a better agreement toward a world with fewer nuclear weapons.” The catch is that Washington wants a better deal that includes China, while China rejects that premise.

China’s Arsenal Has Shifted From Modest to Massive

For decades, China kept a relatively small stockpile, holding near 200 warheads since the 1970s. That is no longer true. A 2025 Pentagon report says China now has more than 600 nuclear warheads and is projected to exceed 1,000 by 2030.

SIPRI data cited in one analysis says China’s stockpile rose from 500 to 600 between 2024 and 2025, a 20 percent jump, described as faster than any other nuclear weapons state.

China is also changing what its force looks like. It is moving from a mainly land based force toward a land air sea nuclear triad. Experts say China now has six nuclear weapons capable submarines, with one at sea at all times. In a public show of force, Xi Jinping presided over a large military parade that unveiled a new ICBM, the DF 61. Tong Zhao says the display aimed “to showcase the fast advancement of China’s strategic capability.”

From Second Strike to War Fighting Capabilities

Traditionally, China was associated with a second strike posture, a smaller force meant to survive an enemy first strike and still retaliate, often described as targeting cities. Now, experts say China is pursuing something more advanced.

Jeffrey Lewis of Middlebury College says, “Xi Jinping wants China to be strong,” and adds, “The Xi Jinping vision is to have a nuclear force that looks more like Russia and the United States,” which hold an estimated 86 percent of the world’s nuclear warheads.

Tong Zhao explains the political logic driving the shift: “President Xi wants a larger nuclear arsenal to counter America’s perception of Chinese strategic inferiority.” The fear, experts say, is that appearing weak could invite pressure or aggression.

Several developments described by U.S. analysts are viewed as destabilizing, not only because of the weapons themselves, but because they compress decision time in a crisis.

One is China’s work on an early warning system that could enable launch on warning, meaning a retaliation could be launched before an incoming strike even detonates. Jeffrey Lewis warns what that posture demands from leaders: “Those systems mean that political leaders have only a few minutes to make the most consequential decision in human history.” He adds, “I’m definitely worried about China joining that club.”

Another concern is the orbital bombardment system China tested in 2021, which could reduce warning time. Tong Zhao says China could use it for surprise attacks on American leadership or nuclear command and control.

China is also developing more dual capable missiles that can carry nuclear or conventional warheads. Lewis warns that, in wartime, uncertainty over what kind of strike is underway “poses all kinds of problems for keeping the nuclear genie in the bottle.”

China’s Intentions: Power, Leverage, and Secrecy

China’s leaders have been tight lipped about the ultimate goal. That opacity is a major driver of anxiety.

Tong Zhao says China is “on the path of a massive nuclear buildup with very little transparency about the end goal,” and that it is “driving a renewed nuclear competition.” Christopher Yeaw echoed that view publicly, saying China has “massively expanded its nuclear arsenal without transparency or any indication of China’s intent or end point.”

Beijing rejects the accusation. In Geneva, China’s ambassador Shen Jian said his country “firmly opposes the constant distortion and smearing of its nuclear policy,” insisting Beijing would not “engage in any nuclear arms race, with any country.” Shen also said China’s arsenal “is not in the same league as the countries possessing the largest nuclear arsenals,” and argued it is “not fair, reasonable or realistic” to expect China to join trilateral talks.

Collaboration With Russia and the Worst Case Scenario

Another layer is the fear of parallel pressure from two nuclear peers. Rose Gottemoeller describes the nightmare scenario U.S. planners worry about: China attacks Taiwan while Russia moves into Europe, “daring the United States to respond.” She calls it “the absolute worst case scenario” in what she labels the “two nuclear peer” problem.

Experts also caution against exaggeration. They say China and Russia remain too wary of each other for full joint nuclear planning or a combined strike threat. But cooperation is growing in technology and signaling. Chinese and Russian nuclear capable bombers have conducted joint patrols over the Sea of Japan and South China Sea, sending messages to Tokyo and Washington.

Are Trilateral Talks Realistic?

Right now, trilateral arms control remains more slogan than structure. The U.S. argues that the post New START era is a chance for a better agreement that includes Beijing. China says that expectation is unrealistic.

Still, there are hints of a narrow opening. A U.S. State Department source told AFP that a “preparatory” meeting took place with a Chinese delegation in Washington the day after New START expired, with a more substantive meeting scheduled in Geneva.

Rose Gottemoeller also points to diplomacy at the top. She notes President Trump will have four opportunities to meet with Xi this year, saying, “There’s a lot of opportunity in 2026 for the U.S. and Russia, and separately the U.S. and China, to come together and talk about reducing nuclear risks and improving nuclear controls.”

The nuclear treaty environment is tenuous because three trends are colliding at once: the end of U.S. Russia limits, China’s rapid and less transparent expansion, and rising suspicion that arms control might be used as leverage rather than restraint.

In this moment, the most dangerous outcome is not only more warheads. It is faster decision timelines, more ambiguous weapons, and fewer guardrails between fear and irreversible choices.