Beijing: North Korea's military commander has said a missile will be fired at Guam by mid August after Donald Trump's "fire and fury" comment shows "sound dialogue is not possible with such a guy bereft of reason and only absolute force can work on him".

The statement released by North Korean state media on Thursday morning came hours after US Secretary of Defence James Mattis warned North Korea not to invite the destruction of its people. 

General Mattis said the "combined allied militaries now possess the most precise, rehearsed, and robust defensive and offensive capabilities on Earth", and North Korea's capabilities were "grossly overmatched by ours".

China's People's Daily was among the world media reporting on the latest North Korean threat, highlighting the statement had said that implementation of the Guam attack would depend on a later decision by North Korean leader Kim Jong-un.

General Kim Rak Gyom, commander of the Strategic Force of the Korean People's Army, said North Korea was examining a plan to fire four Hwasong-12 ballistic rockets as a warning to the US.

He gave details of where the rockets would cross the sky above Japan, and warned they would hit the water 30 to 40 kilometres from Guam.

US Secretary of State Rex Tillerson had a day earlier visited Guam, and assured the American people that they were safe, in an apparent attempt to cool tensions after Mr Trump's comments at a golf resort.

China had called for both sides to step back, with China's Foreign Ministry releasing a statement on Tuesday evening urging "relevant parties" to avoid "escalating the situation with words or actions".

China is urging the US and North Korea to return to dialogue and push for a political solution.

But General Mattis' comments, backing Mr Trump's toughened language, appear to indicate a shift in strategy from the White House in its attempt to bring North Korea to the negotiating table.

A week earlier, Mr Tillerson had pledged that the US was not seeking regime change in North Korea, and Mr Kim needed to stop his missile tests as a pre-condition for talks.

Tough new United Nations Security Council sanctions against North Korea were passed on Saturday, with the backing of China and Russia,.

North Korea complained bitterly that the trade bans that will potentially cut $US1 billion ($1.2 billion) in exports were a threat to its economy and sovereignty.

The North Korean military commander said Mr Trump's "fire and fury" comments were a "load of nonsense" and he failed to grasp the seriousness of the situation.

The official Chinese news agency Xinhua published an editorial on Thursday saying there was no room to "play with fire" on the Korean Peninsula.

"A way out of the nuclear issue on the Korean Peninsula cannot be found in the latest exchange of tough words between Washington and Pyongyang.

"Unless there's a return to reason and a full commitment to a practical and peaceful solution, such a hostile approach will do little but make things worse."

China has called on the US and South Korea to stop large scale military exercises on the Korean Peninsula, in exchange for North Korea agreeing to a weapons freeze, as a precursor for six-party talks. The US has rejected this as rewarding bad behaviour.