North Korea has labelled Joe Biden a "fool of low IQ" and an "imbecile bereft of elementary quality as a human being" after the US presidential hopeful called North Korean leader Kim Jong Un a tyrant during a recent speech.
Pyongyang's official Korean Central News Agency said the former US vice-president had insulted the country's supreme leadership and committed an "intolerable and serious politically motivated provocation" against the North.
Mr Biden during a campaign launch in Philadelphia on Saturday accused US president Donald Trump of cosying up to "dictators and tyrants" like Mr Kim and Russian president Vladimir Putin.
"What he uttered is just sophism of an imbecile bereft of elementary quality as a human being, let alone a politician," KCNA said.
The piece said Mr Biden had "gone reckless and senseless, seized by ambition for power".
It went on to mention apparent Biden gaffes, such as once appearing to fall asleep during a speech by then president Barack Obama.
"It is by no means accidental that here is non-stop comment over his bid for candidacy that he is not worth pinning hope on, backed by the jeer that he is a fool of low IQ," KCNA said.
"Yet he is self-praising himself as being the most popular presidential candidate. This is enough to make a cat laugh."
North Korea has often unleashed crude insults against US and South Korean politicians in past years to criticise what its saw as insults to its leadership or hostile diplomatic and military policies against Pyongyang.
The insults have included racist and sexist diatribes, including when the North called former president Barack Obama "a monkey" and former South Korean president Park Geun-hye, the country's first female leader, a prostitute.
During tensions created by a provocative run in missile tests in 2017, Mr Kim called Mr Trump a "mentally deranged US dotard" after the latter said the US would "totally destroy North Korea" if forced to defend itself or its allies.
The North's description of Mr Trump dramatically improved after Mr Kim initiated diplomacy with Washington and Seoul in 2018 while attempting to leverage his nuclear arsenal for economic and security benefits.
The nuclear negotiations between Washington and Pyongyang broke down in February when a summit between the two leaders collapsed over mismatched demands in sanctions relief and disarmament.