Russia has brought the Soviet-era Perimeter nuclear command system, known in the West as Dead Hand, back into full operation, according to an investigation by The Sunday Times.

The newspaper, working with several research organizations, examined documents covering construction, equipment and military procurement linked to Object 1335, also known by the codename Grot.

The investigation says the complex is located inside Kosvinsky Kamen in the Urals. Over several decades, underground rooms and tunnels, communications centers, life-support systems and equipment connected to the control of strategic nuclear forces were reportedly built there.

According to the investigators, the facility has been significantly expanded, while the infrastructure inside remains operational.

The publication described the system’s main purpose as preserving Russia’s ability to launch a retaliatory nuclear strike if the country’s senior leadership and principal command centers were destroyed and conventional communications channels ceased to function.

The journalists also reported that the modernization of the complex was intended to improve its resistance to modern weapons, including US bunker-busting munitions.

Perimeter was originally developed in the Soviet Union as a backup mechanism for controlling strategic nuclear forces in the event that a large-scale attack destroyed standard communications links and command centers.

The Russian Defense Ministry has neither officially confirmed nor denied the existence of such a system. Perimeter has, however, been repeatedly covered by both Russian and foreign media.