President Donald Trump has launched a scorched-earth attack on Vladimir Putin, warning he has gone 'absolutely crazy' following his latest deadly attack on Ukraine.

In an extraordinary takedown on Truth Social on Sunday night, Trump condemned Putin's 'needless killing [of] a lot of people' as he issued a chilling warning about the future of Russia if the bloodshed continues.

Russia this weekend launched the single largest aerial attack of the war so far - in a direct insult to Trump's efforts at mediation.

'I've always had a very good relationship with Vladimir Putin of Russia, but something has happened to him,' Trump wrote on Sunday.

'He has gone absolutely CRAZY! He is needlessly killing a lot of people, and I'm not just talking about soldiers.