Serhii "Flash" Beskrestnov

Serhii Beskrestnov, known by his call sign “Flash”, is a Ukrainian radio engineer who has become one of the most closely followed public analysts of Russia’s drone technology. Most of what he publishes starts with physical evidence. Soldiers, air-defence crews and investigators send him wreckage and photos, he takes the electronics apart, and he posts what he finds on his Telegram channel, Сергій FLASH | Про технології, which had about 171,000 subscribers in October 2026. Since 17 July 2026 he has been a non-staff adviser to President Volodymyr Zelenskyy on the development of defence technology.

Background. Born in Kyiv in 1974, he graduated in 1997 from the Kyiv Military Institute of Management and Communications, specialising in radio-relay, tropospheric and satellite communications. He then held management posts at two Ukrainian mobile operators, Ukrainian Radio Systems and UMC. From 2009 he ran internet start-ups, among them the video game Isotopium: Chornobyl. He has been a radio amateur since his teens (call sign UT7UD). When Russia invaded in February 2022 he joined the 3rd Special Operations Forces Regiment north of Kyiv and set up military radio communications for the area with the 136th Territorial Defence Battalion. He stayed until Russian forces withdrew. From April 2022 he trained and advised signals and electronic-warfare (EW) personnel of the Armed Forces and National Guard. He wrote guidance manuals on radio reconnaissance and communications, and he sat on the juries of Defence Ministry and Digital Transformation Ministry hackathons. He also crowdfunded radio-monitoring kits and FPV detectors for units, shipping the first 50 monitoring kits in January 2025. He heads the Centre for Radio Technologies, the title under which Ukrainian media quoted him in 2025.

Adviser roles. On 25 January 2026 Defence Minister Mykhailo Fedorov appointed him non-staff adviser on defence technology. The ministry named his priorities as systemic counters to Russian strike and reconnaissance drones, exploitation of captured equipment, and vetting new developments for what works in combat. In announcing the appointment, Fedorov credited him with being the first to report Russia’s use of FPV drones with machine vision and of jet-powered Shaheds. Beskrestnov wrote that he had accepted because the military leadership had been slow to act on his warnings. When Fedorov was dismissed on 15 July 2026, Beskrestnov left the ministry the same evening, as did the fundraiser Serhii Sternenko, another Fedorov adviser. Two days later, after a long meeting with the president, he said he had turned down a post in the new ministry team out of loyalty to Fedorov. He accepted the presidential appointment instead, describing it as a chance to influence technology across the whole defence sector rather than a political role.

The Shahed, piece by piece. His longest-running subject is the Russian Shahed/Geran. In January 2024 he reported the first jet-powered Shahed-238 shot down over Ukraine, with a Chinese engine and a speed above 500 km/h. In March 2024 he described Shaheds sending camera images over Ukrainian 4G. In May 2024 he found radio modems in front-line Shaheds that let operators retask them up to 70 km deep. He then documented the shift to online control. In November 2024 he identified the Chinese XK-F358 mesh modem on the Gerbera. In June 2025 he reported the first Shahed with a camera, a direct radio link from Russia and a machine-vision module. From late 2025 he followed mesh modems in new bands (3200–3400 MHz, then 500–700 MHz) at up to 2×30 W, and found the same modem family on the Molniya, KUB and V2U. Russia was linking its drone types into one radio network: in July 2026 he reported Molniyas being steered through a Gerbera. He traced the trackers too. Two Chinese LTE modems run by a Raspberry Pi report position and engine data, and in April 2026 he wrote that every Shahed carries a SIM card from the Russian operator Tele2 (t2), ordered in batches for the makers. In a September 2026 interview he explained that these SIMs roam on Belarusian networks along the border. He also showed that the modems cannot steer the drone.

Navigation and jamming. Alongside the radio links he tracked the Shahed’s defences against Ukrainian GNSS jamming: CRPA anti-jam antennas growing from 4 to 16 elements by mid-2025, then 32-element antennas marked by Alabuga in October 2026. He explained Ukrainian strikes on VNIIR-Progress in Cheboksary, which makes the Kometa antennas. He reported infrared floodlights and onboard jammers fitted against Ukrainian interceptor drones, and a Shahed carrying a MANPADS (January 2026). In October 2026 he wrote that the “Susanin” optical terrain-matching navigation, already used on Molniya, V2U and Lancet, had appeared on the Geran-4 and Geran-5. He described the Geran-5, built around a Chinese Telefly turbojet, as a budget cruise missile, and the Banderol as a jet loitering munition with a Chinese engine.

Relays over Kyiv. From December 2025 he argued that Shaheds circling for long periods are mesh relays carrying the control link deep into Ukraine. He warned that Russia was looking for Ukrainians willing to host relay boxes in their homes. After a guided jet Shahed hit the SBU building in September 2026 with no other drones airborne, he concluded that an agent had switched on a relay nearby. In October 2026 he said one to three Russian relays were operating inside Kyiv, and he showed mesh modems small enough to hide in a car or a suitcase. Ukrainska Pravda reported the claim and noted that it had not been independently confirmed. In September 2026 he described a Geran-5 strike on Kyiv’s Incom business centre, relayed and filmed by a jet Shahed circling overhead.

Starlink and satellites. In January 2026 he reported the first BM-35 strike drone flown over Starlink and Shaheds using it to hit helicopters. With Fedorov he then worked on the response agreed with SpaceX: a whitelist of registered terminals and other restrictions, whose first effects reached Ukrainian users at the end of January. He apologised publicly to units that lost service. He has since tracked Russia’s satellite alternatives, including Yamal and Express terminals, the portable Spirit-030 and the planned “Rassvet” constellation, as well as Russian jamming of Starlink. On 14 October 2026 he confirmed that SpaceX had capped moving StarShield terminals at 100 mph without warning, disrupting Ukrainian missions, including the interceptors that defend against jet Shaheds.

Front-line electronics. On the front line, his early 2024 reports on fibre-optic drones stand out. In March he described a captured Russian FPV with a 10 km fibre spool, recovered by the unit of Robert “Madyar” Brovdi. Through 2024 he warned that the threat was being underestimated. He documented Russian FPVs controlled over LTE (April 2024), on 500 MHz (summer 2024) and through flying relays. He also took apart Russian jammers such as the Peroed, Silok-01F and Burelom. In 2025 he followed the V2U strike drone as it gained machine vision and lost its last radio link, becoming fully autonomous. In 2026 he followed the antenna-less “AI Molniya”.

Disputes and caveats. He separates findings from inference and labels guesses “only an assumption”. Several of his claims rest on his own analysis, and outlets have said so. Euromaidan Press could not confirm his account of Shaheds broadcasting flight data on FM to paid Ukrainian recorders, and the Kyiv relay estimate has no independent confirmation. He has clashed with the military leadership. In 2024 he wrote that Commander-in-Chief Oleksandr Syrskyi had been told fibre-optic drones were isolated cases. In September 2026 he publicly blamed the former commander-in-chief and his EW chief for a year without systematic work against mesh modems. He has also challenged media reports he considered wrong, among them claims that Shaheds were steered via Telegram (May 2025) and Russian “Lancet over Kyiv” stories (March 2026). On the night of 20 April 2026 four jet Shaheds were launched at his house. One hit the wall and destroyed the house, and he was injured. He said it would not stop him.

Where he publishes. His main channel is Telegram, mostly in Ukrainian and sometimes in Russian. He cross-posts to Facebook and posts video reviews on YouTube. Soldiers can send him finds through forflash.com.ua. He gives long interviews to Ukrainian outlets and YouTube channels, among them ArmyInform, LIGA.net, DOU, Yuriy Romanenko and Alpha Media.