China has labelled a Pentagon report on its growing military strength a "wanton distortion" of the truth, saying it's full of "false comments". 

But the US says China's moves don't match its publicly stated policy of 'no-first-use' of nuclear weapons.

Earlier this month the US Department of Defence publicly released its latest report to Congress on China's ambitions and capabilities. Included in the report were claims like:

• China plans to double its nuclear stockpile over the next 10 years
• China's naval power is now the strongest in the world
• the country is moving to a "launch-on-warning posture", meaning it would counter-attack with nukes as soon as it detected an enemy attack. 

The  Ministry of National Defense People's Republic of China on Monday (NZ time) hit back - with words - saying the Pentagon report "made false comments about China’s normal defense and military construction". 

"Many years of evidence shows that it is the US that is the fomenter of regional unrest, the violator of the international order and the destroyer of world peace," said Col Wu Qian, director of the ministry's Information Bureau. 

He pointed towards US actions in Iraq, Syria and Libya, saying they were directly responsible for 800,000 deaths. 

"We call on the US to view China's national defense and military construction objectively and rationally, cease making false statements and related reports, and take concrete actions to safeguard the healthy development of bilateral military relations."

But the US isn't backing down. Adm Charles Richard, head of the US Strategic Command - which controls the second-largest nuclear arsenal in the world - fears his country is not "fully conscious as a nation of the threats that we face".

"Don't shoot behind the duck, right? It's not where they are, it's where they're going," he told reporters on Monday. 

"And when China sets its mind to something, they are very impressive in their ability to go accomplish it."

He said China built 255 ships for its Coast Guard in just seven years after its formation in 2013.

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"In seven years, they go build 255 on top of all of the other ships they're building. I just think that their strategic forces are next on their to-do list, right, and I'm trying to posture us for the threat that we're going to face, not the one that we have today."

Amd Richard told reporters the evidence collected in the Pentagon report suggested China is "developing a stack of capabilities that, to my mind, is increasingly inconsistent with a stated no-first-use policy". 

He said the US needs to be ready, perhaps relying on much the same theory that saw it get through the Cold War without engaging in nuclear warfare with the Soviet Union - mutually assured destruction.

"The whole idea is to prevent any of that from happening in the first place. The mission is deterrence, and it's sometimes a hard thing to wrap your head around, that in my mission set, victory looks like nothing happened, right? And we have been successful in that inside of - for over 70 years... 

"[It] was not just some accidental fate in history or event in history, it was a lot of hard work by a lot of people to maintain systems ready to go such that we deterred that from happening."

He said the US was not interested in a preemptive strike on China to "deter what they're capable of doing". 

Ironically, China has had a no-first-use policy on nuclear weapons since developing them in 1964. The only other country with such a policy is India.

The US does not have such a policy, reserving the right to use them against any invasion or attack on an ally. The UK, Russia, Pakistan and France have similar stances. 

The US is the only country in the world that's ever used a nuclear weapon in battle - dropping two of them on Japan, hastening the end of World War II. Modern nuclear weapons are capable of much bigger explosions. 

Russia inherited the Soviet Union's nukes when the latter broke up, and maintains the world's largest stockpile. The current US inventory is estimated to be about 15 to 20 times larger than China's. 

Amd Richard was asked about a comment US President Donald Trump made to veteran reporter Bob Woodward, included in his new book Rage, out this week.

Xi is Xi Jinping, President of China, and Putin is Vladimir Putin, President of Russia.

Amd Richard said he hadn't read the book, but he was in charge of "any number of classified capabilities" he described as "quite useful". 

Trump in the past has made strange claims about US military technology, including that the F-35 fighter jet is "literally" invisible.