China pleaded with the United States and North Korea to tone down their fiery rhetoric on Friday as concerns grew that Pyongyang's rogue arms programme could trigger a catastrophic conflict.
Beijing's appeal followed an escalation of a war of words between US President Donald Trump and Kim Jong-Un's nuclear-armed regime.
Foreign ministry spokesman Geng Shuang called on both sides to avoid "going down the old path of alternately showing strength and continuously escalating the situation".
"We call on the relevant parties to be cautious with their words and actions, and contribute more toward easing tensions and enhancing mutual trust," Geng said in a statement.
China has repeatedly called for a resumption of long-dormant six-party talks to peacefully resolve the mounting tensions, but its position has been overshadowed by the emerging game of brinkmanship.
Beijing's proposal for North Korea to suspend its weapons programmes in exchange for the United States and South Korea to halt military drills has essentially been ignored.
President Donald Trump on Thursday hardened his warning that North Korea would face "fire and fury" if it kept threatening the US, saying maybe that tough talk "wasn't tough enough".
Trump also warned North Korea it should be "very, very nervous" of the consequences if it even thinks of attacking US soil, after Pyongyang said it was readying plans to launch missiles towards the Pacific territory of Guam.
The Republican billionaire dismissed any criticism of his "fire and fury" warning of Tuesday, citing threats made by Kim's regime to both Washington and its allies.
"It's about time that somebody stuck up for the people of this country and for the people of other countries. So if anything, maybe that statement wasn't tough enough," Trump said.
Trump also said China, Pyongyang's main diplomatic ally, could "do a lot more" to pressure Kim to end his country's nuclear weapons and ballistic missile programs.
Geng's statement did not address Trump's latest criticism.
US Defense Secretary Jim Mattis, however, appeared to step back from his boss's dire rhetoric, describing the prospect of war as "catastrophic" and adding that diplomatic efforts to solve the North Korea nuclear crisis were yielding results.
Trump's comments, made from his golf club retreat in New Jersey, came after the North announced a detailed plan to send four missiles over Japan and towards Guam, where some 6,000 US soldiers are based.
Pyongyang said the scheme to target the island, a key US military outpost in the western Pacific, was intended to "signal a crucial warning" as "only absolute force" would have an effect on a US leader "bereft of reason".
But in a pointed warning that China may not back its old Korean War ally, a state-run newspaper said Friday that Beijing should not intervene on Pyongyang's side if it triggered a conflict.
Beijing should "make clear that if North Korea launches missiles that threaten US soil first and the US retaliates, China will stay neutral," the nationalistic Global Times said in an editorial.
- 'Better get their act together' -
The tough talk has caused global markets to plunge this week.
Relations between Washington and Pyongyang have been tense for months, in the wake of the North's repeated missile tests, including two successful intercontinental ballistic missile (ICBM) test launches in July that brought much of the US mainland within range.
The barbs have raised fears of a miscalculation that could lead to catastrophic consequences on the Korean Peninsula and beyond.
The region is facing "a mini Cuban missile crisis," John Delury, a professor at Seoul's Yonsei University, told AFP.
In California, Mattis appeared intent on dialing back the tension, explaining his mission and responsibility was to have military options ready "should they be needed" but stressing the US effort is currently focused on diplomacy.
"The tragedy of war is well-enough known it doesn't need another characterisation beyond the fact that it would be catastrophic," he added.
The UN Security Council at the weekend passed a new set of sanctions against Pyongyang over its weapons program, including bans on the export of coal, iron and iron ore, lead and lead ore as well as fish and seafood.
The new punishment could cost North Korea $1 billion a year, and even China voted for the US-drafted proposal.
- Unusual detail -
The North's unusually precise statement regarding Guam said its four missiles would be launched simultaneously and overfly the Japanese prefectures of Shimane, Hiroshima and Kochi.
They would have a flight time of 17 minutes 45 seconds, travel 3,356.7 kilometers (around 2,086 miles) and come down 30 to 40 kilometers away from Guam, it said -- just outside US territorial waters.
Analysts said such a launch would put the US in a dilemma: if it did not try to intercept the missiles, its credibility would be damaged and the North would feel emboldened to carry out a full-range ICBM test.
But if an intercept were attempted and failed in any way, it would undermine the effectiveness of the United States' ballistic missile defense system.
Calls mounted in South Korea for Seoul to develop atomic weapons of its own in light of the situation, with the Korea Herald saying in an editorial: "Now is time to start reviewing nuclear armament.".