A Soviet-era top secret object Duga, an over-the-horizon radar system, once used as part of the Soviet missile defense early-warning radar network, in Chernobyl, Ukraine, Thursday, Nov. 22, 2018. The Duga was closed in 1989 after the 1986 fatal explosion in the 4th unit of the Chernobyl nuclear power plant. (AP Photo/Efrem Lukatsky)