China warned on Tuesday it would "never accept any form of blackmail" after US President Donald Trump said his decision to withdraw from a nuclear pact with Russia was also linked to Beijing's arsenal.

China is not a signatory to the Intermediate-Range Nuclear Forces Treaty (INF), which the United States signed with the then-Soviet Union in the 1980s, but Trump said Monday that Beijing should be included in the accord.

"Now that the United States want to unilaterally withdraw from the treaty, they start to inappropriately speak about other countries," Chinese foreign ministry spokeswoman Hua Chunying told a regular press briefing.

"This approach of shifting the blame on others is utterly unjustifiable and unreasonable," Hua said.

She said China had always pursued a defensive national defence policy.

"We will never accept any form of blackmail," Hua said.

The landmark treaty was signed by Ronald Reagan and Mikhail Gorbachev and led to nearly 2,700 short- and medium-range missiles being eliminated.

It put an end to a mini-arms race in the 1980s triggered by the Soviet Union's deployment of SS-20 nuclear missiles targeting Western European capitals.

"Until people come to their senses, we will build it up," Trump told reporters Monday at the White House, referring to the US nuclear arsenal.

"It's a threat to whoever you want. And it includes China. And it includes Russia. And it includes anybody else that wants to play that game," he said, adding that China "should be included in the agreement".