Beijing: One of China's top diplomats, former ambassador to Australia Fu Ying, has cited an apocalyptic science fiction novel to warn that North Korea and the United States must talk to avoid a tipping point in the Korean Peninsula nuclear crisis.

Madam Fu recounted her personal involvement in talks between North Korea, China and the US in 2003, and gave three possibilities of how the current crisis could end.

Regime change, which she said had been the Obama administration's "main goal" in imposing financial sanctions, may not be realistic in the short term, because Kim Jong-un had stabilised North Korea's domestic situation.

She says North Korea won't give up nuclear weapons to avoid sanctions because the regime started nuclear testing after sanctions began.

"Only through dialogue can mutual security be achieved ... [and] may help wrestle the Korean Peninsula out of its current vicious cycle and prevent North-east Asia from turning into a Dark Forest," she wrote.

The Dark Forest is a Chinese science fiction novel by Liu Cixin in which a former world leader, famous for repelling US invasion, builds a hydrogen bomb to destroy the Earth.

China is attempting to pressure the White House to agree to its proposal for the US to suspend military drills with South Korea, in exchange for North Korea agreeing to freeze its weapons program, as a starting point for dialogue.

Madam Fu's 20,000-word essay published by the US Brookings Institution can be seen as part of that push.

US President Donald Trump said on Monday he would be "honoured" to meet Kim Jong-un "under the right circumstances", but a White House spokesman said later the US would first need to see changes in North Korea's provocative behaviour.

Asked to respond to Mr Trump's comment about possibly meeting Mr Kim, China's foreign ministry spokesman said China encouraged peace talks. "The US and the DPRK [North Korea] as the direct parties in the nuclear issue should take credible efforts at an early date ... for the resumption of peace talks," he said.

Madam Fu, chairwoman of the foreign affairs committee of China's National People's Congress, has argued China has "no leverage" over North Korea without addressing its security concerns.

She recalled how the United States first asked China to mediate with North Korea in 2003. She led the Chinese delegation, and detailed the difficulties of getting the two sides together, when the US clearly was keeping "attack" as an option, and North Korea intended to continue developing nuclear weapons as a back-up.

But she argued the six-party talks that followed were fruitful because they stabilised the situation on the Korean Peninsula and provided several agreements and roadmaps.

"The disruption of the talks was due to a failure to implement those agreements and the nuclear issue has escalated in the absence of talks," she wrote.

Restarting dialogue would be harder because of the level of distrust between the US and North Korea, she wrote.

South Korea's Yonhap news agency reported two US B-1B strategic bombers flew over the Korean Peninsula at the weekend.

US Secretary of State Rex Tillerson said at a UN Security Council meeting on Saturday that North Korea must act first because the US would not reward "bad behaviour".

The US and its allies have called for China to do more in imposing financial sanctions.