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How Russia’s Secret “Harmony” Surveillance Grid Tracked NATO Subs for Years
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![Photo of Vlad Litnarovych]( "Photo of Vlad Litnarovych")
Russia spent more than a decade secretly building an undersea surveillance network in the Arctic using advanced Western technology purchased through shell companies in Europe and Asia, according to an international investigation by the Russian Secrets project—a collaboration involving Norddeutscher Rundfunk (NDR), The Washington Post, Le Monde, Süddeutsche Zeitung, The Times, and other major outlets on October 23.
The covert system, known as “Harmony,” reportedly combines underwater microphones, sonar arrays, and fiber-optic cables to monitor NATO submarine movements in the Barents Sea and beyond.
➡️Exclusive: Our investigation has narrowed down the location of the secret underwater surveillance network ‘Harmonie’.
— Manuel Bewarder (@manuelbewarder) October 23, 2025
Russia uses this network to protect its nuclear weapons. For years, equipment from the West was procured via a corporate network. https://t.co/Fcds9jm5Sl pic.twitter.com/QpwEKzL9Dh
According to the investigation, Moscow used this network to protect its nuclear-armed submarines—a central element of Russia’s second-strike capability—while masking its technology imports through a complex web of front firms.
Researchers found that Russia relied on Western equipment from the United States, Germany, Norway, Japan, and Canada, purchasing sonar systems, subsea drones, and specialized cables over the past decade despite sanctions and export restrictions.
Reveals: How Russia eavesdrops on NATO at sea with technology from the West.
— Selshevneren (@selshevneren) October 23, 2025
For years, Russia has built a secret network on the seabed to eavesdrop on NATO in the Arctic.
SVT together with international media partners, can reveal Russia's surveillance system "Harmony", which was… pic.twitter.com/XfCoXgh3M2
Financial documents, court filings, and intelligence sources examined by Russian Secrets show that the purchases were routed primarily through Mostrello Commercial Ltd, a Cyprus-based company owned by Russian national Alexei Strelchenko.
According to the investigation, Mostrello acted as an intermediary for Russia’s defense conglomerate Kometa, which led the Harmony project.
Between 2013 and 2023, Mostrello and affiliated companies imported more than $50 million worth of Western underwater technology and research vessels, later repurposed for military use in Arctic waters.
Among the acquisitions were sonar and cable systems from German manufacturer Norddeutsche Seekabelwerke, advanced seabed-mapping sonars from Innomar GmbH, and underwater robots capable of operating at depths of 3,000 meters from Forum Energy Technologies in the UK.
In 2015, Mostrello also procured high-speed acoustic equipment from Norway’s Kongsberg Gruppen, according to transaction records reviewed by the journalists.
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“This is Russia’s effort to reduce America’s ability to surveil areas around submarine bases and trail their submarines from point of deployment,” said Bryan Clark, a former US Navy officer and senior fellow at the Hudson Institute. The Harmony system, he added, “allows Russia’s nuclear submarines to move in and out of port undetected.”
According to the researchers, Western intelligence agencies—including the CIA—began tracking Russia’s procurement network as early as 2021.
That same year, US authorities tipped off German officials about the scheme, triggering an investigation that culminated in the arrest of Alexander Shnyakin, a Russian-Kyrgyz businessman who coordinated purchases for Mostrello. Shnyakin was later sentenced in Germany to nearly five years in prison.
According to the findings, despite export restrictions tightened after Russia’s full-scale invasion of Ukraine in 2022, Mostrello continued sourcing equipment from Western suppliers, often using false end-user documentation to disguise its military ties.
In late 2023, the US Treasury Department imposed sanctions on Mostrello, Strelchenko, and several related companies for “laying and maintaining submarine cables for Russian authorities, including the Ministry of Defense.”
Analysts cited in the investigation believe that the Harmony network now forms a semicircular detection barrier from Murmansk to Novaya Zemlya and Franz Josef Land—precisely where Russia’s Northern Fleet and its nuclear submarines are stationed.
The system is believed to detect foreign submarines entering Arctic waters while guiding Russian vessels through “safe corridors.”
Naval experts interviewed by the consortium described Harmony as a major strategic upgrade, potentially comparable to the Cold War–era US SOSUS (Sound Surveillance System).
“It gives Russia early warning and counter-detection capability in one of the most militarized regions on Earth,” one European researcher noted.
Court and corporate documents examined by Russian Secrets show that Western firms often claimed ignorance of the system’s military purpose. In one case, a US manufacturer sold sonar systems to Mostrello under a contract partially written in Russian—but believed at the time the equipment was intended for “cable surveys in the Baltic.”
According to the investigation, tracking the movements of ships purchased by Mostrello helped outline the Harmony system’s likely footprint—spanning the Barents and Kara Seas and shielding Russia’s Arctic nuclear bases from NATO observation.
“Russia has used legitimate European companies as contact points to conceal parts of its supply chain,” said Vice Admiral Nils Stensones, director of Norway’s intelligence service, in comments cited by the report. “This makes it difficult to trace the real end-user.”
The “Russian Secrets” research is based on company data obtained by the International Consortium for Investigative Journalists (ICIJ). Further documents come from the Norddeutscher Rundfunk (NDR) and the Dutch EV magazine Pointer. Journalists from Le Monde (France), L’Espresso (Italy), ICIJ (Washington, D.C.), Kyodo (Japan), NRK (Norway), Pointer (Netherlands), SVT (Sweden), The Times (Great Britain), WDR and Suddeutsche Zeitung (Germany,) as well as The Washington Post were involved in the research. The research was led by NDR.
Earlier, reports emerged that China was accelerating work on a multi-layered ocean surveillance system known as the Transparent Ocean strategy, designed to track submarines from the seabed to space and challenge US and allied undersea operations.
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-4b6d67087ea264339fc0ce363961b255.jpg "Russian Drone Attack in Kharkiv Region Kills Two Men Loading Firewood")
