Russia has been carrying out a large-scale modernization of its nuclear missile infrastructure for several years, according to leaked procurement documents cited by Danish investigative outlet Danwatch and Germany’s weekly news magazine Der Spiegel.

According to the joint report, the documents contain plans for tunnels, control centers and security systems. 

It also includes detailed blueprints of the Strategic Missile Forces bases near the Orenburg region town of Yasny, which is home to Avangard hypersonic glide vehicle, one of Russia’s most advanced nuclear delivery systems.

“It even contains floor plans and infrastructure details for nuclear weapons silos,” the report adds.

According to Danwatch and Der Spiegel, the leaked documents also revealed that over the past decade, numerous nuclear facilities have been demolished and reconstructed with upgraded infrastructure. 

The renovations include hundreds of new barracks, control centers, watchtowers, and underground tunnels linking various buildings across the bases.

The investigation also links European firms, including Germany’s Knauf, to the supply of materials used in the upgrades. 

Although Knauf announced its intention to exit the Russian market in 2024, it remains active through local subsidiaries. The company claims it has no control over how its products are ultimately used.

“Until now, we have only been able to monitor these bases from above using satellite imagery,” Hans M. Kristensen, director of the Nuclear Information Project at the Federation of American Scientists, told the media outlet. “Now, with the help of these unique drawings, we can now for the first time get inside the buildings and all the way underground. It’s completely unprecedented.”

The media outlets reportedly used proxy servers in Russia, Kazakhstan, and Belarus to bypass network restrictions and gain access to the documents.

Russia’s Defense Ministry did not respond to requests for comment.