A former US deputy secretary of state has warned against using "hot rhetoric" as international tensions over North Korea's missile testing continued to escalate.
The rogue state's leader Kim Jong Un has warned Donald Trump he would "pay dearly" after the US president threatened the total destruction of North Korea.
Former US director of intelligence and president George W Bush's ambassador to the UN John Negroponte described the rhetoric as "unhelpful background noise at the very least".
He warned: "It could cause one side or the other to feel that they've been painted into some kind of psychological corner".
Former United Nations secretary general and South Korean diplomat Ban Ki-moon told the BBC: "This level of tension has gone too high, almost to a dangerous level.
"It's not desirable, so we must do all to diffuse the level of tension. I sincerely hope that China really plays much much more seriously some constructive role at this time."
Speaking on Radio 4's Today programme in the UK, Mr Negroponte said: "I'm concerned that it raises the risk of miscalculation, perhaps on both sides.
"I think hot rhetoric is never a very good idea in international diplomacy and I think in this particular case when both sides are brandishing pretty severe threats it seems to me maybe it would be useful if the rhetoric could be toned down a little bit."
He added that "the ground has been set" for Kim Jong Un to at least test more rockets and weapons.
Mr Negroponte said: "Certainly the conventional wisdom has always been that if some kind of military action were taken by us against North Korea that they would immediately retaliate against the south because their border is so close to Seoul (South Korea).
"They could, with conventional artillery and conventional rocketry, attack Seoul almost with impunity."
Commenting on President Trump's approach to the situation, he said: "I think he's learning his job, his learning curve has been steep. I'm not sure he's fully there yet, but I do think his secretary of state and others around him have gained a lot of wisdom."
Mr Negroponte said there was a need to get the players together, starting with the US and China to "see if there are both the carrots and sticks" to get North Korea to abandon its "aggressive behaviour".
He said: "Can the region of North East Asia, can it really live with a nuclear-armed North Korea? That is the key question."
He added: "I'm not ready to make that jump, if you will, to accepting North Korea as a nuclear power. I think it would be dangerous for the peninsula, I think it would be dangerous for the region and I think it would have further deleterious effects on the Nuclear Non-Proliferation Treaty."
China and Britain have agreed to continue to ramp up pressure on North Korea over its nuclear weapons testing.
In a telephone call, British Prime Minister Theresa May and Chinese president Xi Jinping said the two nations have a "particular responsibility" to find a diplomatic solution to the crisis.