Signed in 2010 and extended in 2021, New START capped the U.S. and Russian arsenals at 1,550 deployed nuclear warheads on 700 delivery systems, including intercontinental missiles, submarine-launched missiles, and heavy bombers. 

Despite the treaty, both nations maintain far larger stockpiles: Russia is estimated to have 5,459 nuclear warheads, while the U.S. has around 5,177. New START only applied to deployed strategic weapons, leaving much of the arsenals unrestricted.

For the International Campaign to Abolish Nuclear Weapons (ICAN), the implication is clear: the treaty’s expiration could unleash a new wave of unchecked nuclear risk.

“Without it, the risk of nuclear use will likely increase due to a potential renewed arms race,” the organization said.

Why are there no new agreements?

New START had already been under strain for years. Inspections were suspended during the COVID-19 pandemic, and rising tensions over the Russian invasion of Ukraine led the U.S. to declare Russia in non-compliance in 2023. Russia then suspended its participation, rejecting inspections and data exchanges.

The treaty could have been replaced or extended, but no agreement has been reached. Russia suggested a one-year continuation of the limits, and U.S. President Donald Trump expressed interest in a broader deal including China — but nothing has been finalized.

ICAN emphasized that all nuclear-armed states remain legally obligated to pursue disarmament under the Nuclear Nonproliferation Treaty (NPT). The next NPT Review Conference is scheduled for April to May 2026 in New York.

“At times of high tension among nations, disarmament measures are all the more important,” ICAN said. “The dire international security environment at present, rather than serving as an excuse for inaction, must spur urgent action on disarmament.”

ICAN warned that with the treaty gone, “it is in no country’s interest to increase global nuclear arsenals. All nuclear-armed states should adhere to and implement existing international agreements on nuclear disarmament.”

The expiration of New START leaves the world at a critical juncture. Without enforceable limits on the U.S. and Russia, the risk of miscalculation, escalation, and a renewed nuclear arms race is rising.

The danger, it said, does not come from a single crisis but from several unfolding at once. Growing competition involving Russia, the United States and China has coincided with wars, weakened arms control and a retreat from multilateral institutions.

Scientists pointed to Russia’s war in Ukraine, recent clashes between India and Pakistan, and concerns over Iran ’s nuclear ambitions as increasing the risk of miscalculation. Even limited conflicts, they warned, could escalate quickly.

Climate change is also adding to the risk, with extreme weather events accelerating as governments struggle to agree on meaningful action. The bulletin warned that delays and policy rollbacks are narrowing the window to prevent lasting damage.

Emerging technologies such as artificial intelligence and biotechnology are further raising concerns, as their rapid deployment outpaces global safeguards.

Daniel Holz, chair of the group’s science and security board, said growing “us versus them” thinking is driving the danger. 

“If the world splinters into an us-versus-them, zero-sum approach, it increases the likelihood that we all lose,” he said.

The bulletin said the clock could still be pushed back if countries rebuild arms control, restore climate cooperation and set clear rules for new technologies.

The United States

The United States Navy is the dominant force in this specialised arena. It operates 11 nuclear-powered aircraft carriers, including both the classic Nimitz class and the newest Gerald R. Ford class. These vessels form the backbone of US power projection at sea, able to launch fighter jets, early-warning aircraft and support missions wherever needed in the world.

Ship names like USS Ronald Reagan, USS Dwight D. Eisenhower and USS George Washington are part of this group. They routinely deploy across oceans as part of carrier strike groups, acting as floating bases with global reach and endurance.

This fleet isn’t just powerful but also huge. Nuclear propulsion lets these carriers remain at sea for extended periods, limited only by food and crew endurance rather than fuel. That’s a strategic advantage no other navy currently matches.

France

France stands alone in Europe with a nuclear-powered aircraft carrier in active service: Charles de Gaulle . Commissioned in 2001, it’s Europe’s only carrier of this kind, helping Paris maintain an expeditionary naval presence from the Atlantic to the Indian Ocean.

French defence officials have recently approved plans for a next-generation nuclear carrier to succeed Charles de Gaulle by the late 2030s. This new ship will be bigger and more capable, showing France’s continued commitment to carrier-based power projection.

A nuclear-powered aircraft carrier can operate for 20 to 25 years without refuelling its reactors. Conventional carriers, by contrast, need to refuel every few days or weeks. That difference is enormous.

It allows nuclear carriers to cross oceans, loiter in crisis zones, and respond instantly without depending on fuel tankers. What this really means is freedom of movement. No fuel lines to protect. No ports required.

Foreign media reports have since alleged that Zhang leaked sensitive nuclear weapons information to the United States, accepted bribes to influence promotions and built political cliques within the military.

According to the Wall Street Journal, the accusations were laid out during a closed-door briefing attended by some of China’s highest-ranking officers, hours before authorities announced the inquiry.

The allegations mark an extraordinary fall for a figure long regarded as politically untouchable. Zhang, 75, is a war veteran, the son of a founding PLA general, and a childhood acquaintance of Xi.

He is also one of the few remaining senior commanders with direct combat experience, having fought in China’s brief but bloody border war with Vietnam in 1979.

Nuclear leak

Investigators reportedly linked Zhang to a security breach in China’s nuclear sector uncovered during a separate corruption probe into Gu Jun, a former senior executive at China National Nuclear Corporation.

Gu, who oversaw both civilian and military nuclear programmes, is himself under investigation, and was said to have presented evidence implicating Zhang.

Zhang’s removal also comes amid a broader purge of China’s military leadership, as Xi seeks to reshape the PLA ahead of the Communist Party’s next major leadership transition in 2027.

In October, nine senior generals were removed in a single sweep, including He Weidong, a former second-ranked CMC vice-chair. Another serving CMC member, Liu Zhenli, is now also under investigation.

As a result, the powerful CMC has been reduced to just two members, one of them Xi himself, leaving the body at its smallest size in history.

The shake-up has raised concerns among analysts about short-term disruptions to military decision-making, readiness and operational tempo.

It also casts uncertainty over China’s long-term military ambitions, including Xi’s stated goal of building a “world-class” fighting force by 2049.

US gains confidence

As Beijing grapples with allegations of a major security breach involving its nuclear programme, Washington appears increasingly confident about recalibrating its strategic priorities.

The United States no longer sees China as its top security threat, according to the Pentagon’s 2026 National Defense Strategy, marking a sharp shift from a decade of policy that cast Beijing as Washington’s primary long-term rival.

Instead, the strategy places the defence of the US homeland and the Western Hemisphere at the centre of American military planning, aligning with President Donald Trump’s broader push to “restore American pre-eminence” in the Americas and revive the Monroe Doctrine.

The document calls on allies in Europe and the Asia-Pacific, including South Korea, to shoulder a greater share of their own defence, arguing that the US will no longer compensate for what it describes as allied security shortfalls.

While China remains a concern, the Pentagon says it will pursue deterrence rather than containment, approaching relations through strength, not confrontation and focusing on threats that directly affect US interests.

The shift underscores growing confidence in Washington’s strategic position, even as allegations of internal leaks and leadership turmoil cast fresh doubts over cohesion and trust within China’s military establishment.

And with the PLA still undergoing deep internal turmoil, observers warn that Beijing’s ability to project strength — including towards Taiwan — may be less assured than official rhetoric suggests.

An analysis of 119 seawater samples showed iodine-129 concentrations in the West Philippine Sea — part of the South China Sea that sits within the Philippines’ exclusive economic zone — were around 1.5 to 1.7 times higher than in other Philippine waters.

Researchers said the isotope did not originate locally but likely travelled from further north, pointing to the Yellow Sea as the most probable source.

Previous Chinese studies have linked elevated iodine-129 levels in the Yellow Sea to decades-old nuclear weapons tests and nuclear fuel reprocessing in Europe, with radioactive residues accumulating in northeastern China’s soil and river systems.

From there, scientists believe the isotope was carried into the Yellow Sea and transported southwards through ocean currents, including the Yellow Sea Coastal Current and the Chinese Coastal Current.

While further oceanographic modelling is needed to confirm the exact pathway, the findings suggest radioactive materials can travel thousands of kilometres across national boundaries through marine circulation.

The researchers stressed that the current iodine-129 levels pose no known risk to human health or the marine environment , noting the isotope’s extremely low radioactivity at the concentrations detected.

Instead, they said the discovery highlights iodine-129’s value as a scientific tracer. 

This study highlights the need for stronger international monitoring of radioactive substances in shared waters, particularly in politically sensitive regions where environmental data can carry wider strategic implications.

The research was conducted by experts from the Philippine Nuclear Research Institute, the University of the Philippines Marine Science Institute and the University of Tokyo, with funding from Philippine government science agencies.

“Now I hear that Iran is trying to build up again, and if they are, we’re going to have to knock them down. We’ll knock the hell out of them,” Trump said. He added, however, that he hoped escalation could be avoided, noting reports that Tehran was interested in negotiations. “If they want to make a deal, that’s much smarter,” he said.

Trump said he was not advocating the overthrow of Iran’s leadership, pointing instead to the country’s economic challenges. “I’m not going to talk about overthrow of a regime. They’ve got a lot of problems in Iran. They have tremendous inflation. Their economy is bust,” he said.

Asked whether he would support Israeli military action if Iran continued developing ballistic missiles or nuclear weapons, Trump responded affirmatively. “If they will continue with the missiles? Yes. The nuclear? Fast. Okay. One will be. Yes, absolutely. The other we will do it immediately,” he said.

During the meeting, Trump also praised Netanyahu, describing him as a “wartime prime minister” who had guided Israel through a period of intense conflict . “He’s done a phenomenal job. He’s taken Israel through a very dangerous period of trauma,” Trump said, adding that Israel’s survival had been at stake.

Trump has written to Israeli President Isaac Herzog, urging him to grant Netanyahu a pardon in the corruption cases currently facing the Israeli leader.

The meeting comes ahead of further talks between Trump and Netanyahu, with media reports indicating that the White House is eager to advance discussions on the second phase of the Gaza ceasefire deal. That phase is expected to focus on post-war governance , demilitarisation, and the possible deployment of an international stabilisation force, alongside longer-term reconstruction efforts.

Israel has said the body of the last remaining Israeli hostage in Gaza , Ran Gvili, should be returned as a priority. Significant disagreements remain over what the demilitarisation of Hamas would entail, with Israeli and Hamas positions sharply diverging. Israeli Defence Minister Israel Katz has insisted that the Israel Defence Forces would “never fully withdraw” from Gaza.

The white paper presents China as a supporter of the United Nations-centred global order and a “builder of world peace.” It further reiterates Beijing’s calls for countries to uphold existing treaties on nuclear, biological and chemical weapons and argues that developing nations should have a greater say in international security frameworks.

China says it “conscientiously fulfils” its obligations under major arms control treaties, though several Western governments have previously accused Beijing of opacity in areas such as nuclear modernisation.

The country has further restated its long-held positions on nuclear weapons, including its “ no-first-use ” pledge and opposition to nuclear arms races. It calls for global reductions in nuclear arsenals but does not indicate that China intends to cut its own stockpile, which US intelligence agencies believe is expanding.

China accused unnamed states of destabilising global security through military alliances and missile defence systems.

One of the most important sections concerns outer space, cyberspace and artificial intelligence, areas the white paper calls “new territories of global governance .”

China proposes, amongst others, international norms for cyber operations and global oversight of AI systems with military applications. The document warns that rapid developments in emerging technologies could undermine global stability if not properly regulated.

China says it is strengthening its internal non-proliferation controls and improving oversight of sensitive technologies. It also noted that it is advancing programmes aimed at supporting developing countries to use advanced technologies for peaceful purposes.

The white paper concludes by linking arms control to China’s diplomatic agenda, and calls for an “equal and orderly multipolar world” and a “community with a shared future for humanity”.

China has proposed, amongst others, that the United Nations , not military blocs or unilateral partnerships, should oversee global security frameworks. Adding further that arms control must be rooted in consensus-based multilateral institutions, and calls for developing countries to have a stronger voice in decision-making.

Nuclear governance

On nuclear weapons, the white paper reaffirmed China’s position on such matters, including its commitment to no-first-use and maintaining the “minimum level” of deterrence needed for national security . "China's nuclear weapons are not intended to threaten other countries but for defence and self-protection," the paper said.

China criticises what it describes as “exclusive alliances” and missile defence systems, which it argues undermine strategic stability. "Destroying its abandoned chemical weapons in China is Japan's unshirkable historical, political, and legal responsibility, and also an international obligation stipulated by the CWC," it stressed.

Further, some sections of the White Paper focus on outer space, cyberspace, and artificial intelligence, which the country says are becoming central to global security.

China has thus called for a treaty banning weapons in outer space, UN-led standards for cyber operations, and a responsible and transparent development of military AI.

The country further argued that without global rules, technological competition will become a major driver of instability.

“We're the No. 1 nuclear power, which I hate to admit because it's so horrible. It's such a horrible situation if it ever has to be used,” he said. “Russia's second. China's a distant third. But they'll catch us within four or five years. They want to catch us, and they'll be able to catch us.” 

“We're maybe working on a plan to denuclearize the three of us. We'll see if that works,” he added.

Recently, Trump ordered the Pentagon to resume the testing of nuclear weapons, which, if it is pushed through, will be the first to be conducted since 1992. 

This move came amid an informal global moratorium on nuclear testing, and after Trump accused Russia and China of covert underground nuclear testing. 

While watching out for its competitors, the US has never lost a war , Trump said. 

“Never lost a war. We still don't lose wars. We just sometimes don't fight to win,” he said. 

“We'll stay around the country for 15 years, just bomb the hell out of everybody, make everybody miserable. Nobody knows why we're there.”

“China is committed to peaceful development, follows a policy of 'no first use' of nuclear weapons and a nuclear strategy that focuses on self-defence, and adheres to its nuclear testing moratorium,” Mao said.

Trump had claimed China, Russia , North Korea and Pakistan were all secretly testing nuclear weapons underground. 

He used this claim to preface the resumption of the US’ own tests — the first conducted in more than 30 years. 

“It's hoped that the US will earnestly abide by its obligations under the Treaty and its commitment to a moratorium on nuclear testing, and take concrete actions to uphold the international nuclear disarmament and non-proliferation regime, as well as global strategic balance and stability,” Mao said.

"I think the attack was very important on Iran, because let's say that didn't happen, they'd probably by now have a nuclear weapon, numerous nuclear weapons," Trump said. "And therefore, even if we signed a deal, there'd be a big, dark cloud over it, and it wouldn't be the same thing."

Trump said that Iran had since shown a willingness to engage in diplomacy. "Iran is different. But Iran wants to work on peace now," he added. "They've informed us, and they've acknowledged that they are totally in favour of this deal. They think it's a great thing. So we appreciate that. And we'll work with Iran."