A sign with the radiation warning symbol is seen in front of the construction of the 'Duga' Soviet over-the-horizon (OTH) radar system near Chernobyl on November 22, 2018. - The radar, which was a part of the former Soviet Union missile defence radar system and is now located in the Chernobyl Exclusion Zone, was closed after the Chernobyl catastrophe in 1986. (Photo by Sergei SUPINSKY / AFP)