Russia has withdrawn its troops from the area around Kyiv, pulling them back across the border to Belarus.
But they've left dangerous mines behind, which present an ongoing threat to civilians.
Ukrainian President Volodymyr Zelensky said in his nightly address that the Russian military had left tens of thousands — if not hundreds of thousands — of explosive ordinance behind as they retreated.
Zelensky said the Russian military has left mines in homes, on streets, in fields, around cars and in doorways.
He added that he thought this should be considered a war crime because these mines are designed to injure or kill civilians.