Ukrainian President Volodymyr Zelensky has accused Russia of using "nuclear blackmail" at the Zaporizhzhia nuclear power plant - Europe's largest.
Russia seized the plant in March and has been accused of turning it into a base from where it hits nearby towns.
Both countries have traded blame for shelling it in recent days, prompting UN warnings of a nuclear disaster.
Mr Zelensky says any Russian soldier who shoots at or under the cover of the plant will be a "special target".
The six-nuclear reactor Zaporizhzhia station is located in the city of Enerhodar, on the eastern bank of the Dnieper River (Dnipro in Ukrainian) in southern Ukraine.
Russia invaded Ukraine on 24 February, seizing the plant within days. Moscow has kept Ukrainian personnel to operate the facility.
The UN has warned that continued hostilities around the station could lead to a nuclear disaster affecting much of Europe.
Russia has repeatedly denied any wrongdoing at the plant.
It says it seized control of the plant to prevent leaks of radioactive materials during fighting in the region.
https://www.bbc.co.uk/news/world-europe-62537495