The exchange offer was recounted at the time in congressional testimony by Fiona Hill, who ran Russian and European affairs on the National Security Council during the first Trump administration.
Ukraine's president appointed Chrystia Freeland, a former deputy prime minister of Canada, to a role in which she would advise on postwar reconstruction, if peace talks are successful.
A far-left group took responsibility, saying it was targeting the energy industry. Officials predicted it would take until Thursday to re-establish power in all areas.