US President Donald Trump has said he would not make a peace deal with Vladimir Putin without Volodymyr Zelensky.
Speaking to Fox News Radio before the Alaska summit, the US president said he thought Putin would make a deal, but that it would not come until he met with the Ukrainian president.
"The second meeting will be very, very important, because it will be a meeting where they will make an agreement. And I don't want to use the word 'division.' But you know, to some extent, it's not a bad term, okay?" Trump told Fox News Radio.
European leaders have warned the US president against reaching an agreement without Ukraine and have said that Zelensky must be present for any future talks.
Trump will meet with his Russian counterpart for talks at a US Air Force base in Alaska on Friday.
He estimated that there was a one in four chance that his summit would end in failure and said he was open to imposing further sanctions on Russia if the talks do not lead to peace.
"This meeting prepares for the second meeting, but there is a 25 percent chance that this meeting will not be a successful meeting."
Asked if he would impose sanctions, he replied: "I would, yes... if it is not resolved."