While he called for maximum participation in the upcoming summit in Switzerland, Ukrainian President Volodymyr Zelensky took a swing at Biden, saying the absence of US President Joe Biden from the summit is like giving Russian President Vladimir Putin "a standing ovation."

Biden has not yet confirmed if he will attend the conference set to take place in mid-June. 

During a visit to Brussels, Zelensky said, "If he is not present, it will be just like applauding Putin: personally applauding and doing so standing." 

"I believe that the Peace Summit needs President Biden, and other leaders who are looking at the US response also need him," he added.

Zelensky, who said that dozens of world leaders will attend the summit, stressed that this attendance is a matter of "choice" between advocating for peace or war in Ukraine, stating, "If you want peace, you will be there and you will speak, even if you don't agree with something."

Accusing countries that will not attend as being "satisfied with the war," Zelensky said, "And if you want war, you will go to the mob that Russia wants to organize."

Ruling out Russia's participation and accusing Putin of trying to derail the summit, the Ukrainian President claimed, "Putin is very scared of the peace summit," adding, "He has been trying to thwart this summit and continues to do so."

He also claimed that Russia is "doing everything" for the "further expansion of the war."

Russia not invited, says its absurd 

Meanwhile, the Kremlin slammed today the Swiss summit labeling it as "absurd" because Russia was not invited. 

Kremlin spokesperson Dmitry Peskov told RT, "The conference is, from our point of view, completely hopeless in terms of finding some ways to resolve the conflict around Ukraine," adding, "To seriously talk about these questions without the participation of our country is absurd."

Biden called Putin 'brutal tyrant', vowed open-ended support for Ukraine

With the US presidential elections looming, President Joe Biden called on May 25 the Russian President Vladimir Putin a "brutal tyrant", vowing that the United States "will not walk away" from supporting Ukraine.

In a speech to graduates at the US Military Academy at West Point, Biden said that the United States continues to provide Ukraine with arms and military training.

His statement came as Russian forces are making ground gains across the front line, especially in the Kharkiv region.

Biden claimed that there were "no American soldiers in the war in Ukraine" and that he is "determined to keep it that way."

"But we are standing strong with Ukraine and we will stand with them. We're standing against a man whom I've known well for many years, a brutal tyrant. We may not, we will not walk away," he continued.