In response, Russia has launched a massive drone and missile strike on Ukrainian cities overnight into June 6. The Ukrainian air force said the attack on six Ukrainian regions used more than 400 drones and over 40 ballistic missiles. Several people were killed.

President Donald Trump, after repeatedly promising to quickly end Russia's war on Ukraine, has changed his tune and his attitude dramatically.

But halting progress, ever-more deadly drone attacks and unmoving negotiating positions seem to have taken their toll. On Thursday, Trump used a striking analogy to concede the warfare was nowhere near over, and that he did not, at that moment, feel it was best to intervene.

The large-scale attack comes days after Trump says Putin had "very strongly" promised response to Ukraine "Spider web" attack.

The Russian attacks come after President Donald Trump likened the two sides to children on a playground who needed “to fight for a while.”

Russia's Defence Ministry said on Friday that its forces had carried out a massive and successful strike on military and military-related targets in Ukraine overnight in response to what it called Ukrainian "terrorist acts" against Russia.