SEOUL- Juhyun Lee contributed to this report.
North Korean state media slammed Joe Biden as an 'imbecile' and a 'fool of low IQ' Wednesday, Pyongyang's first substantial comments on the 2020 U.S. presidential election.
The commentary in the state-run Korean Central News Agency criticized Biden for recently referring to North Korean leader Kim Jong Un as a thug and a tyrant.
'[Biden] reeled off rhetoric slandering the supreme leadership of the DPRK,' KCNA said, using the acronym for North Korea's official name. 'What he uttered is just sophism of an imbecile bereft of elementary quality as a human being, let alone a politician.'
The statement does not represent a formal endorsement of Trump; North Korean media often lash out at world leaders who criticize members of the ruling Kim family.
'What is interesting this time is that the North Koreans may be attacking who they figure is Trump's main domestic rival to curry favor with the president,' said Leif-Eric Easley, a professor at Ewha University in Seoul.
Polls indicate Biden leading his Democratic rivals, as well as Trump, in the 2020 race.
The former vice president often criticizes Trump's diplomatic outreach to authoritarian leaders. He recently slammed Kim as a thug.
'He's the same guy (who had) his uncle's brains blown out sitting across a desk,' Biden said earlier this month, referring to Kim's 2013 execution of his uncle and mentor, Jang Song-thaek.
The un-bylined KCNA editorial did not mention Trump. But it did appear to give a nod to Trump's newly rolled out nickname for Biden: 'Sleepy Joe.'
'In April 2011 when the then President [Barack] Obama was in the middle of making a speech, [Biden] was fast asleep in the auditorium,' the commentary said, adding Biden became a 'laughing-stock of the media.'
Trump, who is 72 years old, has attempted to portray Biden, who is 76, as not having enough energy to become president.
KCNA also hit at Biden's reputation for making verbal gaffes.
'Yet, he is self-praising himself as being the most popular presidential candidate,' the editorial said. 'This is enough to make a cat laugh.'
It isn't the first time North Korean media have weighed in during a Trump presidential run. In 2016, an editorial in the DPRK Today, a China-based North Korean mouthpiece, called Trump 'wise' and 'far-sighted,' while slamming his opponent Hillary Clinton as 'dull.'
Even though North Korea has recently taken a more aggressive stance toward the United States, state media have been careful not to criticize Trump. One North Korean official said Kim's relationship with Trump remains "mysteriously wonderful," even though nuclear talks have broken down.
Instead, North Korean state media have slammed other U.S. officials such as Secretary of State Mike Pompeo and National Security Advisor John Bolton.
'Whether the person is Democrat or Republican, North Korean media will always react against someone who insults their leader,' said Yang Moo-jin, a professor at Seoul's University of North Korean Studies. 'And unless Trump calls Kim a dictator or says something harsh, North Korea will not directly criticize the president.'
Soo Kim, a North Korea watcher and former CIA analyst, agrees that Pyongyang doesn't typically endorse U.S. presidential candidates. But Pyongyang clearly wants Trump to remain in office so that negotiations can continue, she said.
Nuclear talks broke down following a Trump-Kim summit in February in Hanoi, Vietnam. The two leaders were unable to agree on how to match the pace of sanctions relief with steps to dismantle North Korea's nuclear program.
Kim has said he will give the United States until the end of the year to change its approach, and has begun testing ballistic missiles for the first time in a year and a half.
Trump has shrugged off Kim's deadline and the missile launches, saying he is in no hurry for a deal.