New START expired: A riskier nuclear era?
With the expiration of New START, the last agreement curtailing the nuclear powers of the US and Russia is no more, ratcheting up a nuclear race that gives China a chance to catch up. Academic Alessandro Arduino explains.
On 5 February, the New Strategic Arms Reduction Treaty (START) expired, ending the last remaining treaty that placed limits on the nuclear arsenals of the US and Russia. A legacy of post-Cold War diplomacy, the New START for more than a decade provided a measure of transparency and predictability between the world’s two largest nuclear powers that today still hold 85% of the world’s nuclear warheads. Its expiration marks the collapse of a framework that once helped manage deterrence, at a moment when it is much needed due to deepening geopolitical rivalries, rising uncertainty and renewed global investment in nuclear weapons.
Beyond the bilateral US-Russia relationship, the global nuclear landscape has grown markedly more volatile since the Cold War bipolar era.
Doomed from the start
Unfortunately, the treaty’s demise has long been expected. Already in 2021, Washington and Moscow agreed to a five-year extension, the final one permitted under the treaty’s terms, without any clear guidelines on how to move forward.
Efforts to negotiate a successor were derailed by a succession of overlapping crises: the Covid-19 pandemic, which halted inspections; Iran’s escalation in enriching weapons-grade fissile material following the collapse of the Joint Comprehensive Plan of Action (JCPOA) nuclear agreement; Russia’s 2022 invasion of Ukraine and its continued nuclear threats toward Europe; and President Trump’s insistence that any future arms control framework has to be trilateral including not only Moscow but also Beijing.
At the same time, China, despite possessing a smaller nuclear arsenal than the US and Russia, is expanding its forces at an unprecedented rate and is not inclined to cap its deterrent by freezing its estimated 600 warheads at today’s levels.
Beyond the bilateral US-Russia relationship, the global nuclear landscape has grown markedly more volatile since the Cold War bipolar era. The DPRK continues to test and develop long-range, nuclear-capable missiles. While reentry vehicles remain a critical weakness in Pyongyang’s arsenal, closer ties between Kim Jong Un and Vladimir Putin could provide access to tested Russian intercontinental ballistic missile technology (ICBM).
Iran’s nuclear ambitions remain a destabilising force in the Middle East, even after Operation Midnight Hammer, which involved the use of the US’s biggest bunker-buster munitions against key Iranian nuclear facilities. In South Asia, India and Pakistan, both nuclear-armed states, have engaged in border clashes involving airstrikes and aerial confrontations, underscoring the risk of escalation between regional rivals.
Russia, meanwhile, regularly invokes nuclear threats toward Ukraine and Europe, highlighting new weapons systems such as the Oreshnik missile and the Poseidon nuclear-powered torpedo. Together, these developments point to a world in which the mechanisms designed to constrain nuclear danger are steadily eroding, even as the number of potential flashpoints continues to grow.
Although Beijing still possesses a smaller stockpile, it has both the time, the will and the industrial capacity to modernise its nuclear forces.
China could take the chance to modernise its nuclear forces
China occupies a central, and increasingly consequential, position in this shifting landscape. Although Beijing still possesses a smaller stockpile, it has both the time, the will and the industrial capacity to modernise its nuclear forces. Alongside the US, China is one of the few powers capable of expanding its arsenal to near parity before eventually accepting limits akin to those once imposed by New START. In this respect, the US Department of Defense estimates that China could field more than 1,000 nuclear warheads by 2030.
China’s nuclear deterrence capabilities, while considered opaque in the past, were on full display during the 2025 Victory Day military parade that offered a public demonstration of this transformation. For the first time, Beijing openly displayed all three legs of a nuclear triad, showcasing capabilities able to reach the continental US.
The land-based component, considered the historical foundation of China’s nuclear deterrent, featured multiple intercontinental ballistic missile systems, including the new DF-61, deployed on road-mobile transporter erector launchers. The air leg was represented by the JingLei-1 (JL-1) air-launched ballistic missile, carried by the H-6N long-range strategic bomber, while the sea leg included the JL-3 submarine-launched ballistic missile, displayed publicly for the first time.
According to the Pentagon’s 2025 China Military Power Report, the JL-3 may have a range exceeding 5,400 nautical miles, allowing it to strike the continental US from waters close to China’s coast. China’s operational Jin-class (Type 094) ballistic missile submarines are capable of carrying multiple JL-2 and JL-3 missiles, reinforcing Beijing’s second-strike capability.
By contrast, the US is struggling to modernise its own ageing nuclear forces, a task complicated by delays, funding shortfalls and conflicting priorities in military materiel procurement and development.
By contrast, the US is struggling to modernise its own ageing nuclear forces, a task complicated by delays, funding shortfalls and conflicting priorities in military materiel procurement and development. Programmes such as the Sentinel ICBM and the Columbia-class ballistic missile submarine (SSBN) remain years behind schedule.
Trapped in renewed uncertainty
The consequences of the collapse of arms control norms extend far beyond the major powers. From ASEAN to the EU, many countries have the most to lose from the erosion of internationally agreed treaties and norms.
Unchecked nuclear proliferation risks empowering states with the means to acquire deterrence, while leaving others trapped in a growing zone of strategic uncertainty. In Europe, debates over nuclear deterrence have resurfaced with renewed urgency. France, Germany, Poland and the UK are closely watching developments, as discussions about a possible European nuclear deterrent, an “Eurobomb” is reemerging.
... without renewed efforts to restore nuclear transparency and predictability, uncertainty will continue to grow in a world that has already shown, at the outset of 2026, an increasing reliance on force rather than diplomacy...
China, unlike smaller and medium-sized powers, has the luxury of time. It can modernise its deterrent while shaping new norms consistent with President Xi Jinping’s Global Security Initiative.
Nevertheless, the expiration of New START underscores a broader reality — without renewed efforts to restore nuclear transparency and predictability, uncertainty will continue to grow in a world that has already shown, at the outset of 2026, an increasing reliance on force rather than diplomacy to resolve international crises. To borrow a phrase favoured by Trump, when President Richard Nixon signed the Strategic Arms Limitation Agreement in Moscow in 1972 with Soviet leader Leonid Brezhnev, it was, by any measure, a good deal.
