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U.S. Accuses China of Covert Nuclear Test in 2020, Raising International Concerns
Washington D.C. – The U.S. government has released new intelligence alleging that China conducted an illicit nuclear test in 2020, a claim that has been forcefully denied by Beijing and met with skepticism by some independent experts.
According to Christopher Yeaw, Assistant Secretary for Arms Control and Nonproliferation at the State Department, a remote seismic station in Kazakhstan detected a minor earthquake on June 22, 2020. This event, registering a magnitude of 2.75, originated approximately 450 miles away at China’s primary nuclear test site, Lop Nur.
Speaking at a Hudson Institute event on Tuesday, Yeaw stated, “There is very little possibility that it is anything other than an explosion, a singular explosion. It is quite consistent with what you would expect from a nuclear explosive test.” He characterized the event as a “yield-producing” nuclear test, implying a chain reaction occurred, and suggested China employed “decoupling” operations to mask its true magnitude.
However, independent experts are not in immediate agreement with this assessment. Ben Dando, head of seismology and verification at NORSAR, a Norwegian organization monitoring nuclear tests, acknowledged that the seismic wave ratios were consistent with an explosion.
Yet, he cautioned that the signal was weak and recorded by only one station, making it difficult to definitively rule out a natural event. “I would not say that there’s really strong conclusive evidence,” Dando told NPR.
“We can’t really confirm or deny whether a nuclear test took place at this point.”
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), whose monitoring station picked up the signal, reported detecting “two very small seismic events, 12 seconds apart.” However, the organization stated that “with this data alone, it is not possible to assess the cause of these events with confidence.”
The Chinese Embassy did not respond to requests for comment, but the Chinese government has vehemently rejected the allegations. Chinese Foreign Ministry spokesperson Lin Jian asserted last week, “The U.S. accusation of Chinese nuclear explosive tests is completely groundless. China opposes the U.S.’s fabrication of pretexts for its own resumption of nuclear tests.”
Testing Troubles and Arsenal Expansion
Major nuclear powers have largely observed a moratorium on nuclear testing for decades. The U.S. last conducted a test in 1992, and China’s last official test was in 1996. Both nations are signatories to the Comprehensive Nuclear-Test-Ban Treaty, which prohibits nuclear testing, although neither has officially ratified it.
While outright testing has ceased, work on nuclear weapons continues. The U.S. employs supercomputer simulations and real-world experiments, including “sub-critical” tests that involve exploding small quantities of weapons-grade plutonium without initiating a nuclear chain reaction.
Meanwhile, satellite imagery suggests significant activity at China’s Lop Nur test site. Tong Zhao, a senior fellow at the Carnegie Endowment for International Peace, notes an expansion of equipment areas, housing, and the digging of at least one new tunnel. “It looks like China is investing significantly into maintaining, if not expanding, the missions at the testing site,” Zhao remarked.
This alleged test comes amid a significant expansion of China’s nuclear arsenal. The Pentagon estimates China’s warhead count has grown from around 200 in 2019 to approximately 600 today, with a goal of 1,000 warheads by 2030. This would bring China closer to parity with the U.S. and Russia.
Given China’s relatively limited nuclear test data (45 tests compared to over a thousand by the U.S.), conducting larger tests could provide valuable insights. Earlier this month, Thomas DiNanno, U.S. Undersecretary of State for Arms Control and International Security, suggested China was already “skirting the line” and planning for future tests with yields in the hundreds of tons.
If the 2020 event was indeed a nuclear test, Dando estimates a magnitude 2.75 event could correspond to an explosion in the tens of tons of TNT. However, he noted that “decoupling” – creating a large cavity for the device – could conceal a much larger explosion, potentially in the hundreds of tons or even a kilotonne.
Zhao believes China might have several motivations for such a test, including developing lower-yield nuclear weapons for potential limited conflicts or testing new designs for hypersonic weapons. He takes the U.S. claims seriously, stating they “may be backed up by some secret U.S. intelligence analysis and it appears consistent with the very active status of China’s Lop Nur nuclear testing site over many years.”
These revelations surface just months after former President Trump indicated the U.S. was also considering a return to nuclear testing “on an equal basis” with other countries. Some experts question the wisdom of the U.S. rushing back to testing, given its extensive historical data.
Yeaw expressed hope for new arms control negotiations with China and Russia but also acknowledged that the Pentagon is considering adding more nuclear weapons to America’s existing arsenal. “There are obviously a bunch of options on the table,” he concluded.