Ukraine is commemorating the 40th anniversary of the Chernobyl nuclear disaster on Sunday amid lingering fears that Russia's 4-year-old war could spark a repeat of the world's worst nuclear disaster.

Kyiv says Moscow has repeatedly sent missiles and drones on a flight path near ?the plant to attack Ukrainian cities, even damaging a critical protective shield in an ?attack last ?year.

Marking the disaster ¡ª which spewed radioactive material across much of Europe despite ?efforts by Soviet authorities to hide the scale ¡ª has taken on sharp new meaning during Russia's invasion of its smaller neighbor.