US Secretary of State Marco Rubio said he did not know whether or not US President Donald Trump would meet with his Russian counterpart Vladimir Putin, Sky News reports.

He added that it depends on how much "progress" can be made on either side.

No call is scheduled between the pair, he said, but they could speak over the next couple of days.

And when asked about secondary sanctions on Russia—looming on Friday—he said Trump will make a decision in the next 24-36 hours.

He said they now have a "better understanding" of the conditions under which Russia would end the conflict in Ukraine.