Ukrainian President Volodymyr Zelensky has defied President Donald Trump and set the stage for a tense White House standoff as he seeks to end the conflict with Russia.

Trump on Sunday demanded Zelensky sacrifice Crimea and give up his desire to join NATO ahead of their blockbuster meeting in the White House on Monday. It will be the first time Zelensky returns to the Oval Office since their famous bust-up in February.

Trump sensationally claimed Zelensky could 'end the war with Russia almost immediately' - a statement which the Ukrainian leader rebuked within 90 minutes.

'President Zelenskyy of Ukraine can end the war with Russia almost immediately, if he wants to, or he can continue to fight,' Trump wrote on Truth Social about 9.20pm on Sunday.

'Remember how it started. No getting back Obama given Crimea (12 years ago, without a shot being fired!), and NO GOING INTO NATO BY UKRAINE. Some things never change!!!'