"We have a very good cooperation with all of them. If there is a need for a larger format, of course, we will join. At the same time, we fully support the Normandy format," he told BNS.
Volker was commenting on a proposal by Ukraine's new President Volodymyr Zelensky that the Normandy Four group, which now comprises Ukraine, Russia, France and Germany, be expanded to include the US and the United Kingdom.
"As I always said, the issue of these meetings has not been a format, the issue has been Russia's political will to implement its obligations under the Minsk agreements," the US envoy said.
"Whatever you can do to facilitate a genuine peace and Russia to implement Minsk agreements, we are ready to join and help," Volker said.
"The Normandy format is meeting in coming weeks. We have close touch with Ukrainians; we have close touch with the French and Germans. If there is a meeting of a different nature, of course we will join, but we are not pushing for that either. We are not worried about the format," he added.
French President Emmanuel Macron has said recently that the Normandy Four may hold a new round of talks in the coming weeks to try to end the conflict in Eastern Ukraine.
Macron said at a meeting with Russian President Vladimir Putin that there was a "real opportunity" for peace in Ukraine following the election of Zelensky.
The United Nations estimates that the armed conflict between the Kiev government and the Russia-backed separatists in Eastern Ukraine has claimed more than 13,000 lives since it broke out in 2014.