The Kremlin said on Wednesday that it was not sure of the veracity of a CNN article that reported U.S. President Donald Trump had once threatened to bomb Moscow to deter Russian President Vladimir Putin from attacking Ukraine.

Russian media have been reacting to Trump's growing criticism of Putin, the most recent being on Tuesday when he accused the Russian leader of peddling "bulls***" over his intentions in Ukraine, after rejecting U.S. ceasefire proposals.

President Trump told donors during a closed-door fundraiser last year that he warned Russian President Vladimir Putin the U.S. would bomb “the s‑‑‑ out of” Moscow if the Kremlin moved to invade