The US says China has plans to double the size of its nuclear weapons stockpile over the next 10 years, including some that can be launched from planes still in the air.
According to the US Department of Defense's (DoD) annual report to Congress, uploaded this week, it's all part of China's 50-year plan to have by 2049 - the centenary of the Communist Party's (CCP) victory in the Chinese Civil War - a "world-class" military.
"Although the CCP has not defined what a 'world-class' military means, within the context of the PRC's national strategy it is likely that Beijing will seek to develop a military by mid-century that is equal to - or in some cases superior to - the US military, or that of any other great power that the PRC views as a threat," the report reads. PRC is short for the People's Republic of China, the country's formal name.
The report outlines how in 2000, US intelligence reported the Chinese military was "sizable but mostly obsolete", its missiles were only short-ranged and lacked accuracy, and its emerging cyber warfare capabilities were "rudimentary".
Since then, the CCP has been working to modernise its force. According to the DoD, it has now surpassed the US in a number of areas - it has a bigger navy, more ground-launched ballistic and cruise missiles - which can travel further - and better air defences.
"The PRC has marshalled the resources, technology, and political will over the past two decades to strengthen and modernize the PLA in nearly every respect."
Since its first nuclear weapons test in 1964, China has steadily increased its stockpile. No one outside of the CCP knows for sure how many there are - with some estimates putting the number in the thousands - but the DoD's current estimate is "in the low 200s".
“Over the next decade, China's nuclear warhead stockpile... is projected to at least double in size as China expands and modernises its nuclear forces," the report reads.
It's estimated about half of the current stockpile are ICBMs - capable of travelling thousands of kilometres.
"The number of warheads on land-based PRC ICBMs capable of threatening the United States is expected to grow to roughly 200 in the next five years."
In addition to increasing the number of land-based missiles, the DoD says China is "pursuing a 'nuclear triad' with the development of a nuclear capable air-launched ballistic missile (ALBM) and improving its ground and sea-based nuclear capabilities".
Part of this will be "moving to a launch-on-warning posture with an expanded silo-based force", the report says. Also known as 'mutually assured destruction', it's similar to how the US and Soviet Union operated during the Cold War - any launch by one side would be met with a launch by the other before it even landed.
The US abandoned that policy in 1997, opting instead not to retaliate until confirming it had actually been hit.
A large part of the report concerns how a war between Taiwan and China might go. China considers Taiwan a part of China, while Taiwan sees itself as a continuation of the pre-PRC Chinese state.
"Taiwan has historically enjoyed military advantages in the context of a cross-Strait conflict, such as technological superiority and the inherent geographic advantages of island defense, but China's multi-decade military modernisation effort has eroded or negated many of these advantages," the report states.
Included are charts outlining the growing imbalance of power between the two rivals - China has 12 times as many soldiers, 11 times as many warships and about five times as many planes, for example. Taiwan has no nuclear weapons.
Writing in Forbes, US military expert David Axe said despite the numerical advantages, Taiwan would be "one of the toughest invasion targets in all the world - something no PLA modernisation program quickly or easily can change".
"Taiwan's defensive advantage is huge. Much huger than [the report] acknowledges. And Taipei is leveraging that advantage by investing in asymmetric capabilities."
The full 200-page DoD report can be read online.