Trump says Friday's Alaska summit with Putin reinforced his belief that peace is "within reach", APA reports citing BBC.
In a "significant step", Putin agreed Russia would accept security guarantees for Ukraine, Trump says.
This is one of the "key points" the leaders will consider at the meeting. He says they will be considering "who will do what, essentially".
Trump says he's optimistic that the group can reach an agreement that will deter future aggression against Ukraine.
"I think the European nations are going to take a lot of the burden," he says. "We're going to help them."
The meeting will also discuss the "possible exchanges of territory", he adds.