The strike set fire to the shelter that contains radiation from the site of the largest nuclear disaster in history, according to Ukrainian officials.

President Volodymyr Zelensky of Ukraine called the damage “significant” but said there were no signs of radiation leaks. A Kremlin spokesman denied that Russia had carried out the strike.

A Russian drone with a high-explosive warhead hit the protective containment shell of the Chernobyl Nuclear Power Plant in the Kyiv region during the night, Ukrainian President Volodymyr Zelenskyy said Friday,