A drone armed with a warhead hit the protective outer shell of Ukraine's Chernobyl nuclear plant. Friday's strike punched a hole in the shell and briefly started a fire. Kyiv blamed Russia, while the Kremlin denied it was responsible. The U.N. International Atomic Energy Agency said radiation levels at the shuttered plant in the Kyiv region have not increased. It said the strike did not breach the plant's inner containment shell. The IAEA did not attribute blame. Fighting around nuclear power plants has repeatedly raised fears of a nuclear catastrophe during three years of war. Chernobyl was the site of the world's worst nuclear accident in 1986.

Despite more than a year of warnings that critical Ukrainian nuclear energy infrastructure sites are vulnerable to potential Russian attacks, Ukraine's Energy Ministry has failed to act swiftly to protect them, government officials have told The Associated Press. Only in the fall, after Ukrainian intelligence agencies warned of potential strikes targeting nuclear transmission facilities, was action taken to begin building protection, the officials said — far too late in the event of an attack. Russia's renewed attacks this winter have heightened scrutiny over these failures. Two years of punishing Russian strikes on its power grid have left Ukraine reliant on nuclear power for more than half of its electricity generation.

The head of the U.N. nuclear watchdog says Russia may eventually restart the Zaporizhzhia nuclear plant that it seized in southeastern Ukraine but shares the view of international monitors that it's not practical and possibly dangerous to do so now. International Atomic Energy Agency Director-General Rafael Grossi said he gained an understanding of Russia's position during a meeting last week in Kaliningrad with Alexey Likhachev, the director-general of the Russian nuclear energy agency Rosatom. Grossi told reporters at a meeting of the IAEA's 35-nation board of governors in Vienna that Russia does "have the intention of using this plant" but that Moscow also recognizes "that at the moment this would be not practical and perhaps even dangerous."