Satellite images appear to show China is making significant progress developing missile silos that could eventually launch nuclear weapons

Rapid construction at three suspected silo fields in China — which could eventually be capable of launching long-range nuclear missiles — appears to indicate that Beijing is putting substantial efforts and resources into the development of its nuclear capabilities, according to analysis of new commercial satellite images.

Experts from the Federation of American Scientists (FAS), a nonpartisan national security research and advocacy organization, found that China has made significant progress on suspected silo fields in the western part of the country. “For China, this is an unprecedented nuclear buildup,” wrote Matt Korda and Hans M. Kristensen, the authors of the FAS report released Tuesday. The authors noted that “the missile silo fields are still many years away from becoming fully operational and it remains to be seen how China will arm and operate them.”

However, recent reports of Chinese activities have added to concerns from US officials about China’s rapid military progress. The suspected development of a first missile silo field was reported in late June. Following another report from FAS released in July on China’s suspected development of a second silo field, US Strategic Command tweeted, “This is the second time in two months the public has discovered what we have been saying all along about the growing threat the world faces and the veil of secrecy that surrounds it.” Navy Adm. Charles A. Richard, the commander of US Strategic Command, said in August that “we are witnessing a strategic breakout by China.”

“The explosive growth and modernization of its nuclear and conventional forces can only be what I describe as breathtaking. And frankly, that word breathtaking may not be enough,” he said. The commercial satellite images from Maxar Technologies and Planet Labs analyzed by FAS offer some of the most detailed pictures yet of three suspected missile silo fields, where the Chinese appear to be constructing roughly 300 new missile silos. “What’s notable, of course, is the scale and the speed of this that this is so out of sync with what the Chinese have done on missile silos ever before,” Kristensen told CNN.