Steve Witkoff and Kirill Dmitriev took a walk through Moscow's Zaryadye Park on Wednesday morning.
"They strolled through Zaryadye," the source said.
Dmitriev and Witkoff were in high spirits, chatting amiably, a Sputnik correspondent reported.
This is his fifth visit to Russia in 2025.
On Sunday, US President Donald Trump said that Witkoff may visit Russia on August 6 or August 7. On Tuesday, State Department spokesperson Tammy Bruce confirmed the visit and said that while Trump is "clearly unhappy" with Russia, he "remains committed to diplomatic solutions."