A drone armed with a warhead hit the protective outer shell of Ukraine's Chernobyl nuclear plant early Friday, punching a hole in the structure and briefly starting a fire, in an attack Kyiv blamed on Russia.

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.

Ukrainian President Volodymyr Zelensky said a Russian drone struck the destroyed nuclear power plant at Chernobyl near Ukraine’s border with Belarus on Thursday night.