U.S. Drops a Nuclear Bombshell: Claims China Conducted a Secret Nuclear Test During the 2020 Galwan Crisis
In a move that has sent ripples through international politics, the United States has publicly leveled a serious allegation against China—claiming that Beijing carried out a covert nuclear test in 2020, at a moment when the world was distracted by the COVID-19 pandemic and India and China were locked in a deadly standoff in the Galwan Valley. This marks the first time Washington has made such an accusation openly.
The charge was made by Thomas DiNanno, Under Secretary at the U.S. State Department, during the United Nations Conference on Disarmament in Geneva on Friday. The timing of the statement is significant. It comes just days after the last remaining U.S.–Russia nuclear arms control treaty expired on February 5, and as President Donald Trump pushes for any future nuclear agreement to include China as a formal participant.
U.S. Intelligence Claims a Hidden Nuclear Test
In a post on social media platform X, DiNanno said the United States possesses intelligence indicating that China has conducted secret nuclear tests designed to evade international monitoring systems. According to him, one such test allegedly took place on June 22, 2020—just seven days after the violent clash between Indian and Chinese troops in eastern Ladakh’s Galwan Valley.
That clash, which occurred on June 15, 2020, resulted in the deaths of 20 Indian soldiers and marked the most serious military confrontation between the two countries in decades. Firearms were banned under existing bilateral agreements, making the hand-to-hand violence even more shocking. China never officially disclosed its casualty figures, though several international reports suggested its losses may have been higher. The prolonged standoff along the Line of Actual Control (LAC) eventually eased only in 2024, following mutual disengagement agreements.
The Alleged Technique: Beating the Sensors
According to the U.S. official, China allegedly used a method known as “decoupling” to conduct the test. In simple terms, this involves detonating a nuclear device inside a large underground cavity, which significantly dampens seismic waves. As a result, global monitoring networks struggle to detect the explosion, allowing the test to slip under the radar.
There are suspicions that the test may have been carried out in Lop Nur, a remote region in Xinjiang, historically associated with China’s nuclear program and located relatively close to India’s border.
Coincidence—or Calculated Timing?
While Washington has not directly linked the alleged nuclear test to the India–China border crisis, the timing has raised eyebrows. Experts point out that tensions along the LAC were at their peak in mid-2020, and the confrontation between two nuclear-armed neighbors had already heightened risks to regional stability.
Some geopolitical analysts argue that if such a test did occur, its planning would have taken months, and the chaos caused by the pandemic and the Galwan clash may have diverted global attention—creating a strategic window for Beijing.
CTBT, Nuclear Arsenals, and Rising Suspicion
China is a signatory to the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which prohibits explosive nuclear tests. However, like the United States, China has not ratified the treaty, leaving room for legal ambiguity.
The U.S. has long expressed concern over China’s rapidly expanding nuclear arsenal, which is estimated to include around 600 nuclear warheads. In November last year, President Trump publicly stated that China and Pakistan were conducting tests, forcing the U.S. to reassess its own preparedness. This concern is a major reason Washington wants China included in any future nuclear arms control framework alongside Russia.
China Pushes Back, CTBTO Finds No Evidence
Beijing has firmly rejected the accusations. Shen Jian, China’s ambassador for nuclear disarmament, stated that China has always acted responsibly in nuclear matters and accused the U.S. of exaggerating a so-called “China nuclear threat” through what he called baseless narratives.
Adding another layer of complexity, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has said that its global monitoring systems detected no signs of nuclear activity in China during the period in question.
A Debate That’s Far From Over
With Washington making unprecedented claims, Beijing pushing back, and international monitoring bodies offering no confirmation, the controversy is far from settled. What is clear, however, is that this allegation is likely to intensify global debates around nuclear transparency, arms control, and strategic stability—at a time when existing safeguards are already under strain.
The issue now sits squarely at the intersection of geopolitics, nuclear deterrence, and great-power rivalry, and its fallout could shape diplomatic negotiations for years to come.