Ukrainian President Volodymyr Zelensky has accused Russia of mining a massive hydroelectric dam upstream from Kherson with explosives, and is calling for international monitors to ensure the security of the site. Ukraine has warned a breach of the dam could lead to catastrophic flooding downstream, impacting hundreds of thousands of people. It could also disrupt critical cooling systems at the Zaporizhzhia nuclear power plant, which relies on water from a reservoir created by the hydroelectric dam.