CHINA is assembling a devastating nuclear arsenal with an array of hypersonic missiles, terrifying "humpback" submarines and hidden desert silos.
Beijing has ramped up military preparations in recent months amid simmering tensions with the White House.
Satellite images reported by NPR show a new tunnel being dug in China's Lop Nur nuclear test site, where China has tested nuclear weapons in the past.
China and a host of other nations committed to a nuclear testing moratorium in the 1990s - and has not conducted full scale nuclear testing since.
However China and other nations including the US have continued to test nonnuclear components of nuclear weapons underground.
It comes after photos emerged of other giant nuclear missile fields under construction in different regions of the country earlier this month.
Jeffrey Lewis, a professor at the Middlebury Institute of International Studies in Monterey, discovered one of the fields on July 2, and told NPR: "Over the past year and a half, China has constructed at least two large facilities, each with more than 100 missile silos.
"China had 18 silos prior to this."
Despite building its nuclear force, China's arsenal still pales in comparison to America's.
China is believed to have around 200 silos though the US has at least twice this amount, Prof Lewis said.
But it marks a shift in China's approach after decades of its 'minimum-deterrent' policy, which saw the country stockpile just a few hundred warheads.
Recent analysis of China's newly commissioned nuclear-powered submarine also suggests it is capable of hitting the US mainland.
A source told the South China Morning Post that the Type 094A, also known as the Jin-class nuclear-powered ballistic missile submarine (SSBN), is capable of firing the JL-3 'Big Wave' missile with a range of over 10,000km.
Drew Thompson, a former US Defense Department official, told CNN that China's nuclear capabilities were evolving slowly.
He said: "China's nuclear force posture has evolved steadily over the past 10 years with road-mobile missile launchers recently joined by the nuclear-capable H-6N bomber, a new submarine-launched ballistic missile, and a growing number of static silos, giving China an increasingly robust and survivable nuclear triad."