ANCHORAGE, United States -- US President Donald Trump on Thursday estimated that his upcoming meeting with Russian President Vladimir Putin in the US state of Alaska has a 25 percent chance of not being successful.

In an interview with Fox News Radio, Trump said his meeting with Putin is like "a chess game," adding that he believes Putin is arriving with the intention of making progress toward reaching a deal on the Russia-Ukraine conflict.

He said if positive progress is made during the meeting, it would lay the groundwork for a second one, which would also include Ukrainian President Volodymyr Zelensky.

Trump on Wednesday warned that Russia would face "very severe consequences" if Putin refuses to agree to a ceasefire in the ongoing conflict with Ukraine.

The Putin-Trump meeting is set for Friday in Anchorage, Alaska.