President Donald Trump has sent a letter of support to Ukraine praising its courage and saying the United States believes in its future as an independent state, as the country marks the anniversary of declaring itself free of Soviet rule.

"Now is the moment to bring an end to the senseless killing," Trump said in a message published by Zelensky on Sunday.

President Donald Trump meets with Ukrainian President Volodymyr Zelensky at the White House in Washington on Monday. Zelensky said he expects to discuss "key issues" at the meeting. It comes after Trump's Friday meeting with Russian President Vladimir Putin in Alaska.