"We held telephone talks on this issue for two days, representatives of the Russian and American administrations," Ushakov told reporters when asked how Moscow learned about US President Donald Trump's proposal for a truce and prisoner exchange with Ukraine.
Services of Russia and Ukraine are supposed to be actively working on the lists of prisoners of war for exchange as part of the agreements, Ushakov said.
"As far as I know, the services are scheduled to be actively working on the lists throughout the day. And if they reach an agreement through their respective communication channels, I believe the exchange will begin. But first, the groundwork needs to be done," Ushakov told reporters.
The groundwork includes making the lists, then finding where the people included in them are being held, then negotiating their exchange and finally, physically transporting them to the agreed place, the Kremlin aide said, adding that all this takes time.
"When it comes to our side, by the way, this was ongoing even before the ceasefire was announced. We passed on the lists to the Ukrainian side, but there was no reaction," Ushakov said.
Therefore, this new exchange may proceed quickly enough, given that Russia has already prepared the lists.
"We will see what will really happen," he added.