US Accuses China of Secret 2020 Nuclear Test

Allegations raise concerns over arms control amid expiration of nuclear treaty

Feb. 6, 2026 at 8:55pm

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The United States has accused China of conducting a secret nuclear test in 2020, alleging that China used techniques to conceal the activity. The accusations were made during a disarmament conference in Geneva, just one day after the expiration of the New START treaty limiting nuclear deployments between the US and Russia.

Why it matters

The US claims underscore rising international tensions over arms control, with the expiration of the New START treaty leaving the US and Russia without binding restrictions on strategic nuclear weapons for the first time in decades. The US is seeking a new, broader nuclear pact that would include China, which has been increasing its nuclear capabilities in recent years.

The details

US Under Secretary of State Thomas DiNanno alleged that China carried out experiments with explosive devices, including preparations for detonations with yields of hundreds of tons, and employed a 'decoupling' technique to reduce the ability of international monitoring systems to detect the nuclear explosions. DiNanno said one such test occurred on June 22, 2020, and that China attempted to hide the activity because it recognized the tests would violate international prohibitions.

  • The US accusations were made on February 7, 2026 during a disarmament conference in Geneva.
  • The New START treaty between the US and Russia expired just one day prior to the US making its accusations against China.

The players

Thomas DiNanno

US Under Secretary of State for Arms Control and International Security who detailed the accusations against China.

Marco Rubio

US Secretary of State who reiterated the intention to maintain a strong nuclear deterrent while exploring avenues for a new, broader arms control agreement.

Shen Jian

China's ambassador for disarmament who did not directly respond to the US accusations but defended China's responsible approach in this area.

China's Ministry of Foreign Affairs

Expressed via social media that China follows a defensive nuclear policy and maintains its arsenal at the minimum level required for national security.

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What’s next

The US is seeking a future nuclear pact that includes China, as part of efforts to avoid a new cycle of international arms racing.

The takeaway

The accusations against China, coupled with the expiration of the New START treaty, highlight a critical juncture in international arms control. Successful negotiations will depend on the willingness of all major nuclear powers to engage in good-faith discussions to prevent a dangerous new arms race.