A former US spy chief has said he fears a war of words between Donald Trump and North Korea could "spiral" out of control into global military conflict.
James Clapper, the ex-Director of National Intelligence, warned the two countries could "blunder" into a Third World War as they exchange escalating hostilities.
His caution came after the US President further ramped up the rhetoric of the nuclear stand-off, vowing North Korea risked being “in trouble like few nations have ever been".
He suggested he had not been "tough enough" when he threatened to unleash "fire and fury" in retaliation to threats by Pyongyang, which responded by claiming it was formulating plans to fire missiles at the US territory of Guam.
"I do worry that this game of rhetoric chicken is going to become self-fulfilling," Mr Clapper told CNN Tonight.
"The President has kind of drawn a red line here and has implied - more than implied - [he would] take some direct action just based on the things that the North Koreans say, which to me is not very responsible."
Mr Clapper, who was Barack Obama's intelligence chief from August 2010 until January this year, added he was worried "that this will spiral out of further control".
"It's somewhat reminiscent to me of the history of World War I and how the world kind of blundered into that. I hope people learn from history here and don't repeat that," he said.
But he added: "I don't think we are there yet. I think there is still time for other measures. Sanctions, diplomacy, all those kind of things."
Mr Clapper served in US intelligence agencies and the military for more than 40 years, working under both Democrat and Republican presidents.
CNN's chief national security correspondent Jim Sciutto suggested the ex-spy chief's warnings should be taken seriously because he "is not someone who tends towards bombastic comments".
"He has genuine concern about the direction of events in North Korea," the journalist added.
Mr Trump's bellicose rhetoric this week rattled both allies and adversaries and led to 60 members of Congress signing a letter of complaint to Secretary of State Rex Tillerson on Thursday.
But the President showed no signs of toning down his hostility after North Korea taunted him as “bereft of reason” and someone for whom “only absolute force can work".
“Frankly, the people who were questioning [my] statement, was it too tough? Maybe it wasn’t tough enough,” he said.
