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

Radiation levels have not increased, Zelenskyy and the U.N. atomic agency said.

Russian officials made no immediate comment, and it was not possible to independently confirm Ukraine’s claim of Russian responsibility.

Zelenskyy said that the drone strike damaged the structure and started a fire, which has been put out.

The International Atomic Energy Agency said the strike occurred at 1:50 a.m. local time (2350 GMT). It said there was “no indication of a breach in the … inner containment” shell.

The shell is a protective cover built around the fourth reactor of the plant, which exploded in 1986, causing one of the worst nuclear accidents in nuclear history.

Built in 2016, the shell is designed to limit the release of radioactivity left in the reactor to the atmosphere.

The three-year Russia-Ukraine war has brought repeated warnings of dangers to Ukraine’s four nuclear plants, especially at the Russian-occupied Zaporizhzhia nuclear power plant in southern Ukraine, which is Europe’s biggest and one of the 10 largest in the world.

IAEA chief Rafael Rossi, said on X that the strike at the CNPP and the recent increase in military activity near the Zaporizhzhia plant “underline persistent nuclear safety risks,” adding that the IAEA remains “on high alert.”

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