But an international war crimes prosecution could deepen Moscow's diplomatic isolation and make it difficult for those accused to travel abroad.
Russia denies deliberately targeting civilian infrastructure in Ukraine, saying its attacks are all intended to reduce Kyiv's ability to fight.
Kyiv says thousands of deported Ukrainian children are being adopted into Russian families, housed in Russian camps and orphanages, given Russian passports and brought up to reject Ukrainian nationality.
Asked if the ICC charges against the Russian officials could include genocide, the source said: "It looks that way."
U.S. national security adviser Jake Sullivan told reporters aboard Air Force One that Ukraine had not confirmed a call between Xi and Zelenskiy.