Gaffe-Prone U.S. President Joe Biden made a big blunder at the NATO Summit. He confused Ukrainian President Volodymyr Zelensky with Russian President Vladimir Putin. Biden referred to Volodymyr Zelensky as his adversary, "Vladimir." On realising his mistake, Biden said, 'Vladimir!?...I shouldn't be so familiar." The U.S. President then quickly corrected himself in the next sentence. But the damage was done, and the American leader is being brutally trolled.