Donald Trump has added economic action to his fiery military threats against North Korea and renewed his rhetorical offensive against Kim Jong Un, calling the reclusive leader "obviously a madman".
The US president's move to punish foreign companies that deal with the North was the latest salvo in a US-led campaign to isolate and impoverish Kim's government until his country halts its missile and nuclear tests.
Mr Trump announced the measures as he met leaders from South Korea and Japan, the nations most immediately endangered by North Korea's threats of a military strike.
"North Korea's nuclear weapons and missile development is a grave threat to peace and security in our world and it is unacceptable that others financially support this criminal, rogue regime," Mr Trump said as he joined Japanese PM Shinzo Abe and South Korean President Moon Jae-in for lunch.
"Tolerance for this disgraceful practice must end now."
Hours later, Kim branded him as "deranged" and warned that he will "pay dearly" for his threat to "totally destroy" the North if it attacks US interests.
The rare statement from the North Korean leader responded to Mr Trump's combative speech days earlier when he issued a warning of potential obliteration for the isolated nation, and mocked the North's young autocrat as a "Rocket Man" on a "suicide mission".
Returning insult with insult, Kim said the president was "unfit to hold the prerogative of supreme command of a country".
He described the president as "a rogue and a gangster fond of playing with fire", and characterised Mr Trump's speech to the world body on Tuesday as "mentally deranged behaviour".
The volley of insults continued on Friday as Mr Trump sent out a pre-dawn Twitter post: "Kim Jong Un of North Korea, who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before!" the president tweeted.
Mr Trump's executive order expanded the Treasury Department's ability to target anyone conducting significant trade in goods, services or technology with North Korea, and to ban them from interacting with the US financial system.
Mr Trump also said China was imposing major banking sanctions, but there was no immediate confirmation from the North's most important trading partner.