Duga (Russian:Дуга) was a Soviet over-the-horizon (OTH) radar system used as part of the Soviet ABM early-warning network. The system operated from July 1976 to December ****. Two operational Duga radars were deployed, one near Chernobyl and Chernihiv in what was then called the Ukrainian SSR (present-day Ukraine), the other in eastern Siberia.