KYIV, Ukraine — Ukrainian President Volodymyr Zelenskyy says Russian forces are trying to seize the Chernobyl nuclear plant.

The plant was the site of the world’s worst nuclear accident when a nuclear reactor exploded in April 1986, spewing radioactive waste across Europe. The plant is located 80 miles north of the capital of Kyiv.

The exploded reactor has been covered by a protective shelter to prevent radiation leaks and the entire plant has been decommissioned.

Zelenskyy said on Twitter that “our defenders are giving their lives so that the tragedy of 1986 will not be repeated.”

He added that “this is a declaration of war against the whole of Europe.”

A Ukrainian official said Russian shelling hit a radioactive waste repository and an increase in radiation levels was reported. The official spoke on condition of anonymity to discuss the sensitive matter.

Russian troops attacked Ukraine on Thursday with Russian President Vladimir Putin ignoring international condemnation and sanctions.

The invasion began with explosions in Kyiv, Kharkiv and Odesa and Putin threatened that attempts to interfere with the attack would lead to “consequences you have never seen.”