Satellite imagery of classified nuclear facilities reveals Beijing's efforts to expand its arsenal just as the last global barriers to nuclear armament are fading, The New York Times reports.
In the lush, misty valleys of southwestern China, satellite photos capture the country's accelerated nuclear buildup—a force designed for a new era of superpower rivalry.
One such valley is known as Zitong in Sichuan province, where engineers are constructing new bunkers and shafts. The new complex is riddled with pipes, indicating the facility handles highly hazardous materials.
In another valley lies the Pingtong facility, surrounded by a double fence. Experts believe China manufactures plutonium pits for nuclear warheads here. The main structure, dominated by a 110-meter (360-foot) ventilation stack, has been upgraded in recent years with new vents and heat dissipators. New construction continues nearby.
Above the entrance to the Pingtong site is a signature call to action from Chinese leader Xi Jinping, painted in characters so large they are visible from space: "Stay true to the founding cause and always remember our mission."
These sites are among several classified nuclear locations in Sichuan province that have expanded and undergone modernization in recent years.
China's capacity building complicates efforts to restore global arms control after the expiration of the last nuclear treaty between the U.S. and Russia. Washington maintains that any subsequent agreements must also bind China, but Beijing shows no interest in participating.
"The changes we see on the ground align with China's broader goals to become a global superpower. Nuclear weapons are an integral part of that," said Renny Babiarz, a geospatial intelligence expert who analyzed the satellite imagery and shared his findings with The New York Times.
He compared each nuclear site in China to a piece of a mosaic that, taken together, demonstrates a pattern of rapid growth. "Evolution has occurred at all these facilities, but generally speaking, these changes have accelerated since 2019," he noted.
China's nuclear expansion has become a source of tension with the United States. Thomas G. DiNanno, a Deputy Assistant Secretary of State for Arms Control, publicly accused China this month of secretly conducting "nuclear tests" in violation of the global moratorium. Beijing dismissed these allegations as false, and experts debate the strength of DiNanno's evidence.
According to the Pentagon's latest annual assessments, China had over 600 nuclear warheads by the end of 2024 and plans to reach 1,000 by 2030. China's stockpile is significantly smaller than the multi-thousand arsenals of the U.S. and Russia, but its growth remains a cause for concern, says Matthew Sharp, a former State Department official and now a senior fellow at MIT's Center for International Studies.
"I think without real dialogue on these issues, which we lack, it's very difficult to say where this is leading, and that is dangerous to me," he said. "Because now we are forced to react and plan based on a worst-case interpretation of a troubling trend."
The Sichuan facilities were built six decades ago as part of Mao Zedong's "Third Front"—a project designed to protect nuclear weapons laboratories and factories from U.S. or Soviet strikes.
Tens of thousands of scientists, engineers, and workers labored secretly to carve into the mountainous terrain what Danny B. Stillman, an American nuclear scientist, later called an "inland nuclear empire."
When tensions among China, Washington, and Moscow eased in the 1980s, many "Third Front" facilities closed, and scientists relocated to a new weapons laboratory in the nearby city of Mianyang. The Pingtong and Zitong sites continued to operate, but changes in the ensuing years were minor, reflecting China's policy at the time of maintaining a relatively small nuclear arsenal.
That era of restraint ended about seven years ago. China began rapidly building or upgrading many nuclear facilities, and construction in Sichuan accelerated as well. This includes a massive laser ignition laboratory in Mianyang, which can be used to study warheads without actual detonations.
The design of the Pingtong complex indicates it is used to manufacture nuclear warhead "pits"—the metallic cores typically containing plutonium. Babiarz noted that the architecture is similar to comparable facilities in other countries, particularly the Los Alamos National Laboratory in the U.S.
In Zitong, the new bunkers and shafts are likely used to test high explosives—chemical compounds whose detonation creates the conditions for a chain reaction in nuclear materials. The complex includes an oval area roughly the size of 10 basketball courts.
The exact purpose of these upgrades remains a subject of debate. Hui Zhang, a physicist at Harvard University, warns that satellite imagery alone provides limited information: "We don't know how many warheads have been produced, we just see the expansion of the plant."
Some of the recent changes may simply reflect security modernization. Chinese engineers may also need new testing areas to adapt warheads for new delivery systems, such as submarine-launched missiles.
Washington's primary concern is how this larger and more modern arsenal might alter China's behavior during a crisis, particularly regarding Taiwan.
China wants to position itself where it will "be largely immune to nuclear coercion from the United States," according to Michael S. Chase, a former Deputy Assistant Secretary of Defense. "They likely believe this could become a significant factor in a conventional conflict over Taiwan."