After New START: Who guards the guardian?

For years, Washington has long self-appointed itself as the custodian of the nuclear order, sanctioning, isolating and threatening states under the banner of non-proliferation. At the same time, the last binding treaty limiting its own strategic arsenal has expired.

On February 5, New START lapsed without replacement. For the first time since 1972, there is no legally binding cap on the world’s two largest nuclear stockpiles: the United States and Russia. The guardian of non-proliferation now stands in a world without guardrails of its own making.

The end of New START risks inaugurating a new phase of nuclear competition, one no longer confined to Washington and Moscow but structured around all major nuclear-armed states.

What followed the treaty’s expiration should concern anyone who believes arms control is grounded in reciprocal restraint rather than geopolitical theatre. Instead of urgently reviving bilateral negotiations with Moscow, historically the only channel capable of producing meaningful reductions between the two dominant arsenals, Washington shifted attention toward Beijing, pressing China to enter trilateral talks.

The dissonance is difficult to ignore. The United States maintains the world’s most extensive network of military alliances, deploys nuclear weapons on foreign soil, modernises all three legs of its nuclear triad, develops new low-yield warheads and retains an ambiguous first-use doctrine. Nevertheless, it positions China as the missing stabilising variable in the global equation.

This is more than diplomatic repositioning. It amounts to a displacement of responsibility at a moment when leadership would logically begin with restoring limits at the top.

According to CNN, some US officials believe the expiration of New START creates strategic space for Washington to expand its nuclear arsenal beyond previous treaty ceilings. As described by a US official, the calculation is that a visible expansion could generate sufficient concern in Beijing to draw China into trilateral arms control negotiations with the United States and Russia.

The logic is leverage through enlargement: expand first, negotiate later.

But such a strategy, if accurately characterised, contains a contradiction. Arms control depends on credibility and mutual assurance. Expanding one’s own arsenal in order to compel another state to accept limitations risks deepening suspicion rather than fostering trust.

In an asymmetrical landscape where the United States and Russia still possess far larger stockpiles than China, expecting Beijing to enter negotiations under conditions shaped by unconstrained American growth may reinforce Chinese caution rather than diminish it.

The pattern intensified almost immediately. A day after the treaty limiting US and Russian missile and warhead deployments expired, Washington accused Beijing of conducting a secret nuclear test in 2020, while simultaneously calling for a broader arms control agreement that would incorporate China alongside Russia.

However, the evidentiary basis of that allegation was publicly contested. Robert Floyd, head of the treaty’s Vienna-based governing body, stated that the organisation’s international monitoring system “did not detect any event consistent with the characteristics of a nuclear weapon test explosion” at the time of the alleged Chinese test. Further detailed analyses, he added, had not altered that determination.

Daryl Kimball, director of the Arms Control Association, argued that if credible evidence exists suggesting that Russia or China conducted secret nuclear tests, the United States should bring that evidence before the treaty’s governing body and pursue technical discussions with both states.

“Any US resumption of testing in response to such allegations would not only be technically unnecessary but foolish and counterproductive because it would set off a chain reaction of nuclear testing by other nuclear-armed states,” he said.

Scholars note a structural irony. As US power faces rising competitors, its policy shifts from cooperative constraint to unilateral freedom. Former disarmament officials warned that some in Washington now advocate expanding the US arsenal to counter China.

“Unfortunately, there are many in Washington, DC, in the Congress, in the Pentagon, and in the nuclear weapons establishment, who are advocating that the United States build up the size of the deployed strategic nuclear force in order to counter China's growing strategic nuclear arsenal in the name of an outdated, Cold-War-era ‘damage limitation’ concept that posits that the United States must hold at risk every adversary nuclear weapon that could potentially strike the U.S. homeland or its allies,” Daryl Kimball said during a joint briefing at the UNGA First Committee on “Advancing Article VI Goals as New START Expires”.

The Long Unravelling

The collapse of New START did not arrive as a bolt from the blue. It stands at the end of a chain.

The Anti-Ballistic Missile Treaty once preserved mutual vulnerability by restricting missile defence systems.

In 2002, Washington withdrew, citing emerging threats. Moscow described the move as “an extremely negative event of historical scale”. The withdrawal once again revealed that a legal restraint would not bind American strategic ambition when perceived advantage beckoned.

The Intermediate-Range Nuclear Forces Treaty followed a similar path. The United States exited in 2019, accusing Russia of violations and pointing to China’s unconstrained missile arsenal. Moscow eventually withdrew as well. The architecture of intermediate-range stability disappeared.

START I and II reduced arsenals in the 1990s, though START II never entered into force. Each agreement required a certain political humility, an acknowledgement that security emerges from mutual limitation rather than technological supremacy.

New START, signed in 2010, capped deployed strategic warheads at 1,550 per side and maintained inspection regimes. Former US president Joe Biden extended it in 2021. But compliance frayed, inspections were suspended and no successor agreement emerged. On February 5, it expired. Moscow announced it was “in principle free to choose” its next steps.

Rather than restoring bilateral ceilings, Washington has emphasised trilateralism. American officials argue that arms control without China is incomplete, calling Beijing’s recent nuclear expansion “destabilising”.

However, China rejects the premise. Chinese officials state that “the nuclear forces of China and the United States are not at the same level at all” and call trilateral demands “unreasonable and unrealistic”. They insist China “will not engage in an arms race with any other country”.

The material context matters. According to the Stockholm International Peace Research Institute, the United States and Russia together account for almost 90 per cent of the world’s nuclear warheads. China’s arsenal, though expanding, remains significantly smaller.

“Even if China reaches the maximum projected number of 1,500 warheads by 2035, that will still amount to only about one third of each of the current Russian and US nuclear stockpiles,” according to the key findings of SIPRI Yearbook 2025.

Observers note that this asymmetry is decisive. Arms control historically begins where the concentration of destructive power is greatest. To demand equal obligations from an actor whose arsenal constitutes a fraction of the dominant powers’ stockpiles risks codifying inequality under the banner of fairness.

The move appears less like universal responsibility and more like strategic redistribution of blame.

China publicly maintains a no-first-use policy and states that its nuclear arsenal is kept at the minimum level necessary for national security. It stations no nuclear weapons abroad, maintains no tactical nuclear weapons and participates in no nuclear alliances. Chinese white papers reiterate that nuclear weapons would be used only in retaliation to a nuclear attack.

In contrast, the United States maintains strategic ambiguity. Its Nuclear Posture Reviews preserve the option of nuclear use in “extreme circumstances”, potentially including certain non-nuclear attacks. It deploys roughly 100 B61 bombs in five NATO countries under “nuclear sharing” arrangements. Through AUKUS, it transfers nuclear submarine technology to Australia. It modernises its triad and fields low-yield warheads such as the W76-2.

American officials describe this as sustaining a “robust, credible, and modernised” deterrent.

However, critics call this expanding nuclear usability and blurring the boundary between nuclear and conventional war. The structural contrast is clear: one state emphasises minimum deterrence and territorial defence; the other maintains a globalised deterrence posture embedded in alliance systems and forward deployments.

Under these conditions, Washington’s insistence that Beijing must first accept trilateral parity appears politically convenient.

Meanwhile, the expiration of New START casts a shadow over the upcoming review of the Nuclear Non-Proliferation Treaty. Article VI commits nuclear-weapon states to pursue negotiations on disarmament in good faith.

South Africa’s disarmament minister warned that New START’s lapse leaves “no legally binding risk reduction constraints on the world’s two largest possessors of nuclear arsenals” and “accelerates strategic instability.” The UN Office for Disarmament Affairs warned of “negative implications” for the Review Conference.

The NPT rests on a grand bargain. Non-nuclear states renounce atomic weapons permanently. Nuclear-weapon states pursue reductions.

As modernisation accelerates and treaty ceilings vanish, the non-proliferation bargain begins to look hollow, raising a pointed question for the United States: can a state that modernises extensively, preserves an ambiguous doctrine, deploys weapons abroad and withdraws from successive treaties still credibly claim moral leadership in non-proliferation?

The credibility crisis lies here.

Observers note that hegemony carries obligations. Power is not neutral, as it shapes the rules of the system. When a hegemon designs treaties, enforces norms and then abandons constraints once relative power shifts, the system destabilises.

The United States faces strategic competition in a multipolar world. The temptation is to prioritise flexibility over binding limitation. However, flexibility for the strongest often translates into insecurity for others.

Pressuring China into trilateral negotiations without first rebuilding bilateral restraint suggests a reluctance to accept asymmetrical responsibility. It implies that the rising power must be incorporated into the constraint before the dominant power demonstrates renewed commitment.

Responsibility, however, flows first from concentration of power. The states with the largest arsenals carry the heaviest burden.

Sleepwalking or Strategy?

Sleepwalking implies unconscious drift, flattering policymakers. However, policy choices are deliberate.

Over the past two decades, nuclear policy has unfolded through conscious choice rather than drift: the withdrawal from the ABM Treaty, the exit from the INF Treaty, the steady modernisation of the triad, the expansion of alliance-based nuclear deployments, the lapse of New START without replacement, and the mounting pressure on China to enter trilateral talks.

The pattern suggests a hegemon navigating relative decline by preserving manoeuvrability rather than recommitting to limitation.

Analysts note that the way forward is conceptually straightforward. Washington can return to bilateral negotiations with Russia, restore inspections and data exchanges, demonstrate verifiable restraint, reduce deployed warheads below expired ceilings, clarify or narrow first-use doctrine and reassess overseas deployments.

Without such visible recommitment at the top, multilateral arms control will lack credibility and the normative foundation of non-proliferation will erode, encouraging wider proliferation and raising the structural risk of catastrophe.

The sleepwalk can be interrupted. Responsibility cannot be outsourced.