To mark the Russian invasion of Ukraine, a special edition on episodes from Ukrainian history.

In April 1986 a reactor exploded at the Chernobyl nuclear power plant in Soviet Ukraine. Sergii Mirnyi monitored radiation levels in the exclusion zone around the plant. How the international community - including both Russia and the USA - offered security "assurances" to Ukraine in return for giving up its share of the Soviet nuclear arsenal. A survivor's account of Ukraine's great famine in the 1930s, the Holodomor, when several million people died. The mass killing of Ukrainian Jews by Nazi Germany during World War Two, and how Artek, on the shores of the Black Sea in Crimea, became the Soviet Union's most popular holiday camp.

Photo: The Chernobyl plant shortly after the explosion in 1986 Credit: Getty Images