North Korea has referred to Joe Biden as an "old man in senility," after his typically personal assault on Russian President Vladimir Putin accusing him of "war crimes" in Ukraine.

Biden's tirade came after he dubbed Russian President Vladimir Putin a "war criminal" and demanded that he be tried for alleged atrocities against people in Ukraine's Bucha.

Read more: West to try dissolving Bucha truth in demagogic reasoning: Lavrov

Earlier, US President Biden also called for regime change in Moscow, alarming allies and triggering panic in Washington that tried to downplay his remarks.

In response, former US President Donald Trump accused Joe Biden of possibly provoking Vladimir Putin into a nuclear war after the US president called for the Russian President's removal.

The former US President tried to undo the damage from what is seen as Biden’s biggest gaffe since coming into office.

Biden said, “For God’s sake, this man cannot remain in power," triggering panic in the White House, which rushed out a statement insisting that “regime change” in Moscow was not on the administration’s agenda.

However,  in an interview with Newsmax, Trump said he feared the damage had already been done.

"When you put him into a corner and you talk the way they're talking – they're talking weak – and they're almost giving him an incentive," Trump said. "They're handling him very badly, in my opinion."

Read more: WSJ: Biden should avoid public speaking

According to a commentary by the official KCNA news agency on Saturday, "The latest story is the US chief executive who spoke ill of the Russian president with groundless data."

"Such reckless remarks can be made only by the descendants of Yankees, master hand at aggression and plot-breeding," it added.

The commentary referred to the American President as a "president known for his repeated slip of tongue."

Read more: Biden confuses "Ukrainian" for "Iranian" in speech

"The conclusion could be that there is a problem in his intellectual faculty and that his reckless remarks are just a show of imprudence of an old man in his senility," continued the commentary.

"Gloomy, it seems, is the future of the U.S. with such a feeble man in power."

Read more: North Korea: US to blame for Ukraine crisis

Pyongyang has also supported Moscow in its operation war in Ukraine, accusing the US of being the "root cause" of the issue.