Russia tells US, N Korea 'hot heads' to calm down

Russian FM Sergey Lavrov describes war of words between Washington and Pyongyang a 'kindergarten fight'.

Russia's Foreign Minister Sergey Lavrov has urged "hot heads" to calm down, calling an escalating war of words between US President Donald Trump and North Korea's Kim Jong-un "a kindergarten fight".

Trump called the North Korean leader a "madman" on Friday, a day after Kim dubbed him a "mentally deranged US dotard" who would face the "highest level of hard-line countermeasure in history" in retaliation for the US president saying Washington would "totally destroy" the Asian country if it threatened the US or its allies.

Kim Jong-un calls Donald Trump 'deranged'

"We have to calm down the hot heads," Lavrov told reporters at the United Nations on Friday, where world leaders gathered this week for the body's annual General Assembly.

"We continue to strive for the reasonable and not the emotional approach ... of the kindergarten fight between children."

On Thursday, North Korea's Foreign Minister Ri Yong Ho warned that Kim could consider a hydrogen bomb test of an unprecedented scale over the Pacific.

Ri, who is due to speak to the UN on Saturday, added that he did not know Kim's exact thoughts.

In response, US Secretary of State Rex Tillerson said Washington's diplomatic efforts would continue but all military options were still on the table.

Japan, the only country ever to suffer an atomic attack, described the threat from Ri as "totally unacceptable".

For its part, China, North Korea's neighbour and only major ally, responded by calling on all parties to exercise restraint.

EXPLAINER: Hydrogen bomb v atomic bomb - What's the difference?

"For now, it is a war of words but diplomats increasingly fear the heightened rhetoric, coupled with any miscalculations, could lead to actual conflict," Al Jazeera's James Bays, reporting from the UN headquarters in New York, said.

Graham Ong-Webb, a research fellow at the S. Rajaratnam School of International Studies in Singapore, said that a prospect of a major international conflict seemed to be down to two men "on opposite sides of a fence" slinging insults and threats at each other.

"What we need to do is deflate the issue and really get down to the table and encouraging parties to start talking," he told Al Jazeera from Singapore.

"Because if we do not do so, we are just going to drive ourselves against a wall and head towards conflict."