US conducts nuclear blast detection test to catch rivals’ ‘decoupled’ detonations

The U.S. energy department’s National Nuclear Security Administration (NNSA) has conducted an underground chemical explosive test in Nevada to study how difficult-to-detect nuclear blasts could be identified. The experiment took place at the Nevada National Security Site and was designed to improve detection of low-yield explosions linked to potential testing by China and Russia. The non-nuclear test took place inside a tunnel at the site, which is about 65 miles northwest of Las Vegas. The location was also used during the development of the first U.S. nuclear weapons. NNSA said Wednesday that measurements collected during the experiment will help scientists improve models and algorithms used to identify and characterize foreign nuclear detonations. Testing a harder-to-detect explosion The experiment used a conventional chemical explosive, with no nuclear weapon or nuclear detonation involved. It focused on a method known as “decoupling,” which can reduce the signals produced by an underground explosion. NNSA said the test was intended to strengthen U.S. capabilities for identifying what it described as a “decoupled” explosion. The agency linked the test method to what the United States determined China conducted at its Lop Nur nuclear test site in June 2020. “Just as a stealth aircraft looks smaller on radar, decoupling can greatly muffle the signals detected by nuclear detection sensors, making a large explosion appear smaller,” the statement said. In a conventional underground test, a device is placed deep underground near surrounding rock. The resulting shock waves travel through the ground and monitoring equipment can detect them. A decoupled test uses a large underground chamber that can reduce the seismic signals reaching sensors. Sensors capture data from the blast Researchers used several types of advanced sensors during the experiment to study the explosion and its effects. The equipment included accelerometers and seismometers for measuring ground motion. The test also used infrasound sensors, electromagnetic sensors, chemical and radiotracer samplers, and meteorological instruments. NNSA said the collected measurements will support scientific models and help refine detection algorithms. The broader objective is to improve how scientists estimate the characteristics of underground explosions. Better measurements could help U.S. monitoring systems identify nuclear detonations and determine their properties when they occur. NNSA did not provide a date for the experiment. Test follows calls to resume nuclear testing The announcement comes after President Donald Trump called for the United States to resume underground nuclear weapons testing. In October 2025, Trump said he had instructed the Pentagon to immediately restart nuclear testing on an equal basis with China and Russia. “We’ve halted [testing] many years ago, but with others doing testing, I think it’s appropriate to do so,” he said at the time. No U.S. underground nuclear weapons test has taken place since that announcement. The latest Nevada experiment does not represent a return to nuclear explosive testing. The United States has maintained a moratorium on nuclear explosive tests since 1992. Get the latest in engineering, tech, space & science - delivered daily to your inbox.A versatile writer, Sujita has worked with Mashable Middle East and News Daily 24. When she isn't writing, you can find her glued to the latest web series and movies.