As the race for the 2020 presidential election gathers pace, the bitter war of words between US President Donald Trump and his main political rival Joe Biden is expected to escalate.
Seen as the frontrunner for the Democratic nomination, Mr Biden has been the main target of Mr Trump’s verbal broadsides so far.
But some insults, it seems, go too far, even for President Trump.
On Sunday Mr Trump tweeted a rare, albeit backhanded, defence of Mr Biden in response to a vicious verbal attack by North Korea.
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The surprising tweet was addressed to “Mr Chairman”, an apparent reference to North Korea’s leader Kim Jong-un.
In the tweet, Mr Trump said although Mr Biden was “sleepy and very slow”, he was “not a rabid dog”, as North Korea had called him.
The president’s comments were included in a retweet of a conservative commentator’s post about North Korea’s attack on Mr Biden.
North Korea had lambasted Mr Biden for having the “temerity to dare slander the dignity” of its leader, Mr Kim.
“Rabid dogs like Biden can hurt lots of people if they are allowed to run about,” a statement, carried North Korea’s official KCNA news agency, said on Thursday. “They must be beaten to death with a stick.”
It is not clear what drew the ire of North Korea, though Mr Biden has been critical of the Trump-Kim summits this year and last.
In response to the North Korean jibe, Mr Biden said he saw such insults “as a badge of honour”.
In contrast, Mr Trump’s relationship with Mr Kim has been more amicable as he seeks to convince North Korea to give up its nuclear weapons through summitry rather than threats.
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Mr Trump has lavished Mr Kim with compliments, describing him as “very sharp” and a “real leader”.
Mr Biden, on the other hand, has frequently been on the receiving end of Mr Trump’s jibes.
The impeachment inquiry, which centres on whether Mr Trump withheld military aid from Ukraine in exchange for an investigation into Mr Biden and his son, has intensified their long-running feud.