Russian authorities say at least two people were injured in an explosion Tuesday at an ammunition depot in annexed Crimea.
Ukraine has not claimed responsibility for the incident, which follows last week's explosions at a Russian airbase on the peninsula.
Russian Defense Minister Sergei Shoigu has said Moscow "has no need" to use nuclear weapons to achieve its goals in Ukraine and said advanced US weapons are not having a "significant impact" on the war.
Ukrainian President Volodymyr Zelensky has called for tougher sanctions against Russia for "nuclear blackmail" over the Zaporizhia nuclear power plant.
The city of Nikopol, across the river from the Russian-occupied nuclear power plant,