U.S. Secretary of State Rex Tillerson said on Wednesday it was important for U.S. President Donald Trump and Russian President Vladimir Putin to have a "good exchange" over how they see the nature of the bilateral relationship.

"I would say at this point it's difficult to say exactly what ... Russia's intentions are in this relationship," Tillerson said before he left Washington for the Group of 20 summit in Hamburg, Germany.

"And I think that's the most important part of this meeting is to have a good exchange between President Trump and President Putin over what they both see as the nature of this relationship between our two countries," he said.