An explosion at the Chernobyl Nuclear Power Plant in 1986 spread a radioactive cloud over large parts of the Soviet Union, now the territories of Belarus, Ukraine and the Russian Federation. Nearly 8.4 million people in the three countries were exposed to the radiation.

On 8 December 2016 the United Nations General Assembly adopted a resolution designating 26 April as International Chernobyl Disaster Remembrance Day. In its resolution, the General Assembly recognised that three decades after the disaster there remains persistent serious long-term consequences and that the affected communities and territories are experiencing continuing related needs. The General Assembly invites all Member States, relevant agencies of the United Nations system and other international organisations, as well as civil society, to observe the day.