Russia is modernising a secret underground complex inside Mount Kosvinsky Kamen in the Urals, which is linked to the “Perimeter” strategic nuclear forces back-up command-and-control system.
This is reported in an investigation by Danwatch.
The report concerns Facility 1335, also known by the codename “Grotto”, located in Sverdlovsk Oblast.
According to the investigators, Russia’s Ministry of Defence began the main modernisation work on the complex in 2018. In state defence procurement documents for 2018–2024, journalists found thousands of orders linked to Facility 1335.
The purchases include at least 22,000 tonnes of steel, more than 56,500 tonnes of cement, around 600 km of electrical cables, 21 electrical substations, 182 ventilation units, 95 pieces of heavy machinery, and equipment for drilling into rock.
Russian military buyers also procured ventilation systems, filters to protect against radioactive dust, blast-resistant equipment, and communications gear.
According to the investigation, the documentation mentions at least 24 underground rooms for which a compressed-air system was installed. The main and emergency exits from the complex are located about 2.5 km apart.
In 2019, refrigeration equipment with a total capacity of around 5 MW was purchased for Facility 1335. Journalists suggest it may be used to remove heat from communications systems, computing equipment, and electrical equipment capable of operating continuously.
Satellite images also recorded large-scale earthworks and construction near the entrances to the complex. According to Danwatch, the Russian military was creating new entrances into the mountain and carrying out work inside the underground system.
The “Perimeter” system, often referred to in the West as the “Dead Hand”, is a Soviet-era—and now Russian—back-up command-and-control system for strategic nuclear forces.
It was created during the Cold War to preserve the ability to deliver a retaliatory nuclear strike if the main command posts were destroyed and communications with the leadership were cut.
At the same time, details of how the system works remain classified. Therefore, the widespread claim that it can fully automatically launch Russia’s entire nuclear arsenal requires clarification.
According to the Dossier Centre, as far back as the 2000s a new element of the system—developed as part of its modernisation—was installed at Facility 1335. Experts believe the current work is an attempt by Russia to preserve and renew the complex’s operational capability.
Russian authorities have officially acknowledged the existence of “Perimeter”. In 2011, the commander of the Strategic Missile Forces, Sergei Karakayev, confirmed that it existed.
In 2025, former Russian president Dmitry Medvedev mentioned the “Dead Hand” in a post addressed to US President Donald Trump.
Journalists also found evidence of the system’s modernisation directly in Russian military publications. Veterans of the Strategic Missile Forces say that after modernisation, “Perimeter” was returned to a state of combat readiness.
Retired Major General Viktor Khalin, who took part in developing the system’s original version and worked on its modernisation in 2005–2010, wrote about updates to the automation system and the strengthening of its technical capabilities.
According to him, the system received, among other things, mobile command posts and space-based communications channels. In 2023, as claimed in Russian military publications, the system was once again put on “combat readiness”.