Former U.S. Vice President Joe Biden on Tuesday said he would not meet with North Korean leader Kim Jong Un — who once lambasted Biden as a rabid dog — without “preconditions,” as President Donald Trump has done three times.

Biden, asked at the evening’s Democratic presidential debate in Iowa if he was willing to sit down for talks with the leader of the nuclear-armed country, said Trump’s meetings with Kim had been a gift to the young dictator, bestowing him with a sense of “legitimacy.”

The former senator and vice president said the meetings had weakened crushing economic sanctions against the country that many experts believe brought Kim to the negotiating table in the first place.

Biden said his approach to dealing with the North would include working to repair relations between South Korea and Japan to better combat any provocations while also heaping “enormous pressure” on China “because it’s also in their interest” to rein in Pyongyang’s nuclear activities.

In November, North Korea launched the latest in a series of insults at Biden, calling him a “rabid dog” who is greedy for power and deserves to be beaten to death.

The attack came after Biden issued a statement attacking Trump’s North Korea policy and referring Kim as a “murderous dictator” — an accusation tantamount to treason in the North.

In response, North Korea unleashed a barrage of barbs, calling Biden “a rabid dog only keen on getting at others’ throats” and a “profiteer.”

“A crow is never whiter for often washing,” the official Korean Central News Agency said in a commentary.

“Anyone who dare slanders the dignity of the supreme leadership of the DPRK, can never spare the DPRK’s merciless punishment whoever and wherever,” it said, referring to the acronym for the country’s official name, the Democratic People’s Republic of Korea. “And he will be made to see even in a grave what horrible consequences will be brought about by his thoughtless utterances.”

Misspelling Biden’s name as “Baiden,” it compared him, again, to a rabid dog, that “can hurt lots of people if they are allowed to run about.” Such a beast, it went on, “must be beaten to death with a stick, before it is too late. Doing so will be beneficial for the U.S. also.”

It was not the first time Biden had invited criticism from the North. In May, it called him a “fool of low I.Q.” for referring to Kim as a dictator and a tyrant.

In his presidential campaign, Biden has been sharply critical of Trump’s policy on North Korea, calling it a diplomatic failure but refraining from laying out any clear policies of his own for the seemingly intractable nuclear issue.