Five years ago, on April 26, 2016, Ukraine commemorated the 30th anniversary of the Chornobyl nuclear disaster.
Sirens were sounded in the early morning hours on April 26 in Ukraine to mark 30 years since the moment that the first explosion blew the roof off the building housing a reactor at the Chornobyl nuclear power plant that sent a cloud of radioactive material high into the air, drifting into Russia and Belarus and across northern Europe.