Ukrainian forces strike Saransk plant — Russia’s main producer of fiber optic cables used in combat drones

On the night of April 5, Ukrainian drones attacked the Optic Fiber Systems plant in Saransk. The facility, previously partially owned by the state nanotechnology group Rusnano, produces fiber optic cable used in drones and is the only plant of its kind in Russia. The Russian Telegram channel Baza reported a fire in the area, while the local authorities confirmed that “one of the enterprises was attacked by drones.” The strike was geolocated by analysts from the Ukrainian Telegram channel CyberBoroshno.

According to data obtained by The Insider, as of 2024 Optic Fiber Systems JSC was still importing components that were crucial for Russia’s efforts to substitute for Western-made technology. The company placed orders for Chinese preforms, as well as polymer coatings and hardeners. The primary non-civilian consumers of this the company’s products are manufacturers of combat drones for the Russian military.

Fiber optics for drones

The pro-Russian open source intelligence (OSINT) project LostArmour has documented over 200 instances of KVN-type drones using fiber-optic control cables in attacks on Ukrainian military equipment between November 2024 and April 2025, based on video evidence. These drones are more frequently used against personnel, though the total number of such strikes is unknown.

In September 2024, Alexey Chadayev, director of the Ushkuy Research Center, which developed the KVN, stated that the drone had been used nearly 1,000 times, with cable breaks occurring in 1–2 out of every 10 launches (meaning 10–20% of drones failed to reach their target). As of January 2025, 100 combat crews had been trained to operate KVN drones. In November 2024, Ushkuy was one of the winners of a Ministry of Industry and Trade competition to create regional drone centers, receiving nearly 500 million rubles in funding.

The KVN and Hortensia fiber-optic drones were showcased at the “Army 2024” expo. Chadayev stated that KVN drones are used to target armored vehicles, radar systems, electronic warfare equipment, and enemy strongpoints.

The Hortensia drone, developed by a design bureau of the same name, is reportedly capable of firing a suspended RPG-26, automatically locking onto the target before launch. This mechanism, according to the developers, allows the drone to bypass interference from Ukrainian electronic warfare systems. However, The Insider could not confirm combat use of Hortensia in this configuration. Verified instances only involve a traditional setup, with an explosive charge mounted directly on the drone.

Russia is also using FPV drones called Piranha in combat. These drones, which can carry up to 4.5 kilograms of payload, are made by engineers at the Piranha Design Bureau in Ulyanovsk.

Optic Fiber Systems' international contracts

Russia currently produces around 50,000 fiber-optic-controlled drones per month and plans to increase that number. According to market experts interviewed by The Insider, this could require up to 6 million kilometers of fiber annually — one-third more than Russia’s current total yearly production.

Meanwhile, imports of fiber-optic cable into Russia are steadily declining. Customs data reviewed by The Insider shows just $28 million worth of imports — nearly half the value from the previous year. According to TAdviser, Russia produced 4.45 million kilometers of optical fiber in 2023, using a mix of domestic and Chinese fiber.

In 2011, Optic Fiber Systems signed a contract with Finnish equipment maker Nextrom Oy, which provided technology and built the plant turnkey. As recently as 2021, the company was still sourcing parts from Finland, Germany, and Japan, but shifted entirely to Chinese suppliers after the war began. Based on imports of Nextrom furnace parts, the Saransk facility remains the only user of this equipment in Russia.

The plant houses three drawing towers and six production lines, each capable of producing 2,000 km of fiber daily. Actual output is much lower: in 2021, the company produced 2.5 million kilometers of fiber. Since then, production has fluctuated between 1 and 2 million kilometers annually.

According to company materials, Russian producers cover about a quarter of domestic demand. The rest comes from imports or cables assembled from imported fiber. Although President Vladimir Putin ordered a “full production cycle” in this sector in 2023, no independent preform manufacturing has been launched. Optic Fiber Systems claimed in 2023 that it was developing project documentation. Similar promises were made by Rostec and Shvabe JSC, but no confirmed launch has been reported.

Despite its strategic importance, the company operates in a semi-transparent manner: it has not published financial reports since 2021 and is not subject to international sanctions. Former shareholders included Rusnano, the Republic of Mordovia (via the regional Sozidanie fund), and entities believed to be affiliated with Gazprombank.

Production volumes

Optic Fiber Systems claimed that in 2024 it produced 1.1 million kilometers of fiber from preforms — glass tubes made of ultra-pure quartz used in fiber production. The company handled most of the preform imports itself. According to Rusnano, as of 2023, this was the only fiber-optic manufacturer in Russia.

That year, Russia imported $7.5 million worth of quartz preforms. Given the average price of $86 per kilogram (based on volza system data), that would yield approximately 2.7 million kilometers of fiber — not counting defective output.

In addition to preforms, the company also imports epoxy acrylates and UV curing systems. Customs data confirm these purchases are made openly, without shell companies.

A webinar hosted by the company — “Fiber Optics Made in Russia: 2024 Results and Plans for 2025” — stated that total fiber consumption in Russia last year was around 4.5 million kilometers. Based on Saransk’s output, domestic production covered 25% to 50% of demand.

Plant shutdown could last months

Military analyst Leonid Dmitriev told The Insider that despite relatively minor external damage, the April 5 drone strike may have long-term consequences. He said damage to clean rooms and precision equipment — which require calibration accuracy down to 0.4 micrometers — could significantly delay production. According to Dmitriev, restoring operations to full capacity will take time.

The Russian Telegram channel Voenny Osvedomitel confirmed Dmitriev’s assessment, reporting that while the attack won’t affect supply to the front lines, restoring the facility will take months. Analysis of publicly available footage shows damage to the building’s exterior but no sign of fire spreading inside. The drone struck a stairwell and a personnel corridor — non-critical parts of the plant. The main equipment in the center of the building was unharmed.

Experts estimate that emergency recovery and partial restart could take about a month. However, since most drone manufacturers are not affiliated with the Russian Defense Ministry and source their fiber from China, frontline supply is expected to remain unaffected. The Saransk plant mainly serves other clients and is not directly tied to small-scale drone producers.

How fiber optics work

Fiber optics operate on the principle of total internal reflection. At the core is a hair-thin strand of quartz glass with a higher refractive index than the surrounding cladding. Light entering at a certain angle reflects within the core and does not escape. The fiber is fragile and must be protected from environmental damage with layers of polymer and metal — creating a fiber-optic cable.

During production, the preform is slowly melted in a graphite furnace under an inert gas atmosphere and drawn into a fine strand. The fiber is then coated with UV-curable acrylic and hardened. After quality checks, the fiber is either sent to cable manufacturers or used bare — such as in drones.