US Levels Serious Accusations Against China Over Alleged Secret Nuclear Test
In a dramatic escalation of geopolitical tensions, the United States has publicly accused China of conducting a clandestine nuclear test in 2020. The revelation, delivered by a high-ranking US official at an international disarmament forum, comes at a precarious moment for global nuclear security. With the expiration of the landmark New START treaty between the US and Russia, the world now faces an era without binding limits on the nuclear arsenals of its two largest superpowers for the first time in over five decades.
Undersecretary of State for Arms Control and International Security Thomas DiNanno made the bombshell announcement during remarks at the global Disarmament Conference in Vienna on Friday. 'Today, I can reveal that the U.S. Government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons,' DiNanno stated. He specifically pointed to a test on June 22, 2020, describing it as a 'yield-producing nuclear test' that violated international commitments on nuclear testing.
Declassified intelligence, as confirmed by a former senior US official, underpins these claims. DiNanno further alleged that the Chinese military employed sophisticated methods to conceal the explosion, including 'decoupling'—a technique involving the creation of large underground caverns to dampen seismic signals and evade global monitoring systems. This obfuscation, he argued, demonstrates China's intent to bypass the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which it has signed but not ratified.
Background: The Collapse of New START and Rising Nuclear Anxieties
The timing of the US accusation could not be more critical. Just a day prior, the New START treaty—signed in 2010 to limit deployed strategic nuclear warheads, missiles, and bombers between the US and Russia—officially lapsed without renewal. This agreement had been a cornerstone of arms control since the end of the Cold War, capping each side at 1,550 deployed warheads.
President Donald Trump's administration has been vocal about its dissatisfaction with the treaty's narrow scope, which excluded China. Trump himself has advocated for resuming US nuclear testing, a policy shift that harks back to the era before the 1992 moratorium on American tests. In 2025, during a military parade in Beijing showcasing land-based intercontinental ballistic missiles, China signaled its own ambitions, further fueling concerns about an emerging three-way arms race.
Experts warn that without renewed constraints, nuclear modernization efforts by all three powers could spiral unchecked. 'The lapse of New START removes the last formal barrier to arsenal expansion,' said Dr. Elena Vasquez, a nuclear policy analyst at the Arms Control Association. 'China's alleged test adds urgency, as it suggests Beijing is advancing its capabilities in ways that could destabilize the balance of power.'
China's Response and Denials
Beijing has swiftly denied the allegations, labeling them as 'baseless smears' aimed at justifying US military buildup. A spokesperson for the Chinese Foreign Ministry reiterated that China adheres to a 'no first use' nuclear policy and has not conducted nuclear tests since 1996. However, satellite imagery and seismic data analyzed by Western intelligence have long raised suspicions about activities at China's Lop Nur test site in Xinjiang.
The use of decoupling, as described by DiNanno, is particularly concerning to non-proliferation advocates. This method reduces the seismic footprint of an explosion, making it harder for the International Monitoring System—a network of sensors established under the CTBT—to detect violations. While not foolproof, it allows plausible deniability, a tactic that could embolden other nations to skirt international norms.
Trump's Vision: A Broader Nuclear Agreement Involving China and Russia
The Trump administration is leveraging this moment to push for a comprehensive nuclear deal that includes all major players. 'We need a new framework that addresses the threats from Moscow and Beijing, not just one adversary,' a White House official told reporters. Trump has previously floated ideas for a 'grand bargain' that would encompass tactical nuclear weapons, hypersonic delivery systems, and cyber threats to nuclear command structures—areas untouched by previous treaties.
This call aligns with broader US strategy under Trump, which emphasizes deterrence through strength. In his 2025 State of the Union address, the president highlighted investments in next-generation nuclear capabilities, including low-yield warheads and enhanced missile defenses. Critics, however, argue that such moves could provoke rather than pacify, potentially accelerating China's arsenal growth, which US estimates peg at over 500 warheads and rising toward 1,000 by 2030.
Implications for Global Security and Diplomacy
The accusation ripples far beyond bilateral US-China relations. Russia, already modernizing its forces with new Sarmat ICBMs, has expressed openness to talks but insists on parity. At the Vienna conference, delegates from the European Union and Japan urged immediate multilateral negotiations to prevent a 'nuclear winter' scenario.
From an economic perspective, renewed arms racing could divert trillions from pressing global challenges like climate change and pandemics. For the US, domestic debates intensify: progressives decry the erosion of disarmament goals, while hawks praise the transparency as a wake-up call.
Looking ahead, the path to a tripartite agreement remains fraught. China has historically resisted caps, viewing them as infringing on its sovereign development. Yet, with the UN Security Council in deadlock and non-state actors eyeing nuclear black markets, the stakes for diplomacy have never been higher.
Expert Analysis: Is This the Spark for a New Cold War?
Nuclear historians draw parallels to the 1970s SALT talks, when US-Soviet détente briefly stabilized arsenals. But today's multipolar world, with China's economic clout and Russia's assertiveness, complicates matters. 'Verification will be the sticking point,' notes arms expert Mark Fitzpatrick of the International Institute for Strategic Studies. 'China's opacity on military matters could derail even the best-intentioned pact.'
Public sentiment in the US, per recent CNN polls, shows growing unease: 62% of Americans view China's nuclear buildup as a top threat, up from 45% in 2020. As the Trump team engages envoys from Beijing and Moscow, the world watches anxiously. Will this accusation catalyze cooperation or catastrophe? Only time—and transparent dialogue—will tell.
In the meantime, the international community grapples with a sobering reality: the nuclear shadow lengthens, demanding bold leadership to pull back from the brink.