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.

Ukraine said a Russian drone crashed into the containment structure, starting a fire, but so far radiation levels have stayed constant.

A Russian drone struck the former nuclear power plant at Chernobyl in an attack overnight into Friday, Ukrainian President Volodymyr Zelensky has said.

Ukraine’s nuclear ghosts have been stirred up again after a drone armed with a warhead hit the protective outer shell of the plant at Chernobyl, the site of the world’s worst nuclear accident.

The outer shell that was struck is a protective cover built in 2016 over a heavy concrete containment structure. Soon after the 1986 disaster, the inner layer (in which there was no indication of a breach on Friday morning), was placed on the plant’s fourth reactor. The containment shells seek to prevent radiation leaks.

Ukrainian President Volodymyr Zelenskyy said a Russian drone struck the protective covering of the nuclear reactor that exploded at Chernobyl in 1986.