China may have secretly set off low-level underground nuclear test explosions despite claiming to observe an international pact banning such blasts, the U.S. State Department said in a report in April that could fuel U.S.-Chinese tensions.
The finding, first reported by the Wall Street Journal, may worsen ties already strained by U.S. charges that the global COVID-19 pandemic resulted from Beijing’s mishandling of a 2019 outbreak of the coronavirus in the city of Wuhan.
U.S. concerns about Beijing’s possible breaches of a “zero yield” standard for test blasts have been prompted by activities at China’s Lop Nur nuclear test site throughout 2019, the State Department report said.
Zero yield refers to a nuclear test in which there is no explosive chain reaction of the type ignited by the detonation of a nuclear warhead.
“China’s possible preparation to operate its Lop Nur test site year-round, its use of explosive containment chambers, extensive excavation activities at Lop Nur and a lack of transparency on its nuclear testing activities … raise concerns regarding its adherence to the zero yield standard,” the report said, without providing evidence of a low-yield test.
Beijing’s lack of transparency included blocking data transmissions from sensors linked to a monitoring centre operated by the international agency that verifies compliance with a treaty banning nuclear test explosions.
The 1996 Comprehensive Test Ban Treaty (CTBT) allows activities designed to ensure the safety of nuclear weapons.
A spokeswoman for the Comprehensive Test Ban Treaty Organization, which verifies compliance with the pact, told the Wall Street Journal there had been no interruptions in data transmissions from China’s five sensor stations since the end of August 2019 following an interruption that began in 2018.
Chinese foreign ministry spokesman Zhao Lijian told a daily briefing in Beijing that China was committed to a moratorium on nuclear tests and said the United States was making false accusations.
“China has always adopted a responsible attitude, earnestly fulfilling the international obligations and promises it has assumed,” he said.
“The U.S. criticism of China is entirely groundless, without foundation, and not worth refuting.”