Archive · 1 Oct 2026
US Conducts Experiment to Improve Nuclear Blast Detection
The United States conducted a test using chemical explosives, not a nuclear weapon.
The test happened underground at a US test site in Nevada.
Scientists used special materials called radiotracers to collect information.
They want to improve systems that can detect small nuclear explosions.
The experiment focused on explosions designed to be harder to detect with earthquake-monitoring tools.
The United States had accused China of conducting such a test in 2020.
China said that accusation was completely unfounded.
The new data will help US scientists improve their detection models and computer programs.
The National Nuclear Security Administration conducted a subsurface, non-nuclear chemical high-explosive experiment on Wednesday.
The test took place in the P Tunnel at Area 12 of the Nevada National Security Site.
Radiotracers and chemical high-explosives were used during the experiment.
Collected data will help validate scientific models and refine nuclear-explosion detection algorithms.
The experiment followed US allegations that China conducted a decoupled nuclear test in June 2020, which China denied.
- Who
- The US National Nuclear Security Administration conducted the experiment; China was involved in the related US allegation, which it denied.
- What
- A subsurface, non-nuclear chemical high-explosive experiment aimed at improving detection of low-yield or decoupled nuclear explosions.
- When
- Wednesday, Sept. 30.
- Where
- The P Tunnel in Area 12 at the Nevada National Security Site.
- Why
- To collect data for validating scientific models and refining algorithms used to detect nuclear explosions.
United States Position
China's Position
Alleged 2020 nuclear test
United States Position
The United States alleged that China conducted a secret, decoupled nuclear test in June 2020 and said improved detection capabilities were needed.
China's Position
China called the US allegation entirely unfounded and said it was an attempt to fabricate excuses for resuming US nuclear testing.
Need for broader arms control
United States Position
The United States raised the allegation while calling for a new, broader arms control treaty.
China's Position
China rejected the allegation and characterized it as justification for a possible US return to nuclear testing.
- Conducting agency
- US National Nuclear Security Administration
- Experiment type
- Subsurface, non-nuclear chemical high-explosive experiment
- Location
- P Tunnel, Area 12, Nevada National Security Site
- Materials used
- Chemical high-explosives and radiotracers
- Detection focus
- Low-yield and decoupled nuclear explosions
- Data purpose
- Validation of scientific models and refinement of detection algorithms
- Related allegation
- The United States accused China of conducting a decoupled nuclear test in June 2020; China denied the allegation