Thieves have stolen electronic equipment from a Russian military aircraft known as a "doomsday plane" for its role in the country's nuclear arsenal, local media report.
Reports say unknown thieves broke into the Ilyushin Il-80 plane at an airfield in the southern region of Rostov.
It is unclear when the incident took place, but 39 units of equipment and five radio boards were taken.
The local government said an investigation was under way.
Military experts say the aircraft is one of four Il-80s designed to be used as airborne command posts for Russian officials, including the president, in the event of a nuclear conflict. Interfax news agency describes them as among Russia's most classified aircraft.