‘They cannot be jammed': fibre optic drones pose new threat in Ukraine

The Guardian

23-04-2025

On the battlefields of Ukraine, new sights emerge. Thread-like filaments of wire, extended across open fields. Netting rigged up between trees along key supply roads. Both are responses to a hard-to-detect weapon able to sneak into spaces previously thought safe, hi tech and low tech all at once.
At a secret workshop in Ukraine's north-east, where about 20 people assemble hundreds of FPV (first person view) drones, there is a new design. Under the frame of the familiar quadcopter is a cylinder, the size of a forearm. Coiled up inside is fibre optic cable, 10km (6 miles) or even 20km long, to create a wired kamikaze drone.
Capt Yuriy Fedorenko, the commander of a specialist drone unit, the Achilles regiment, says fibre optic drones were an experimental response to battlefield jamming and rapidly took off late last year. With no radio connection, they cannot be jammed, are difficult to detect and able to fly in ways conventional FPV drones cannot.
'If pilots are experienced, they can fly these drones very low and between the trees in a forest or tree line. If you are flying with a regular drone, the trees block the signal unless you have a re-transmitter close,' he observes. Where tree lined supply roads were thought safer, fibre optic drones have been able to get through.
A video from a Russian military Telegram channel from last month demonstrates their ominous capability. A fibre optic drone, the nose of the yellow cylinder housing the coil clearly visible, flies with precision a few centimetres from the ground, to strike a Ukrainian howitzer concealed in a barn, a location clearly previously considered safe.
Soldiers have quickly come to fear them. Oleksii, a combat medic, working in Pokrovsk, the busiest front in Ukraine's east, says daytime evacuations of the wounded, already very difficult, have become impossible. 'It's just not happening now there are fibre optic drones. They cannot be jammed and for now they are the main concern for the guys on the frontline,' he said.
But as Fedorenko acknowledges, it is Russia that, at least for now, 'is well ahead of us' – largely because Moscow has had greater access to fibre optic cabling, with Ukraine scrambling to catch up. Fibre optic drones were heavily used in Russia's counterattack in Kursk and experts believe they were an element in Moscow's success in largely rolling up Ukraine's salient in March.
Experts estimate that drones of all types now contribute to about 70% to 80% of military casualties on both sides. As for fibre optic craft, Samuel Bendett, a drone expert with the Center for Naval Analyses, said they appear to be proving useful at the start of an assault, in an environment where cheap remotely piloted vehicles are increasingly taking the place of artillery.
'Since these drones cannot be jammed by electronic warfare, they're used as a first wave of attack to target adversarial electronic warfare and jamming capability. That then clears the way for regular radio-controlled FPV drones to strike,' he said. Because they are wired, they also deliver high quality images of the target – useful for battlefield intelligence – 'up until the last second of the strike'.
At the urban workshop, part of the Achilles regiment, Dmytro, gives a tour. A conventional FPV drone can cost $400 (£302), excluding the price of its explosive payload, but the cable adds the same amount again. There are complications with the equipment, the cabling is sensitive to damage and its connector to contamination with dust – but the biggest problem is retraining drone pilots.
'I think each operator [pilot] will have five or six failed missions [in training],' Dmytro says because the craft handles differently. Ten kilometres of fibre optic cable weighs approximately 1.2 to 1.4kg, inevitably transforming how the drone flies through the air. But with drones already the primary weapon on an expanding battlefield, both sides have tens of thousands of pilots ready and willing to learn.
The question now is whether fibre optic drones become even more important. Dmytro estimates that about a tenth of the workshop's drone output consists of fibre optic drones, in line with estimates from analysts such as Bendett. This week, Ukraine's president, Volodymyr Zelenskyy, discussed the drones with his senior military commanders in Ukraine's general staff.
'Since the beginning of this year, more than 20 new certified drone models with fibre optic control systems have emerged. Eleven of our Ukrainian enterprises have already mastered the production of such drones,' Zelenskyy said, promising to ramp up production as soon as possible. Unlike the early days of the war, drone supply of all types to the military is increasingly dominated by the Ukrainian state, not donations.
A week earlier, Ukraine's chief military commander, Gen Oleksandr Syrskyi, reported that '77,000 enemy targets' were engaged and destroyed by drones of all types. On fibre optic drones in particular, the general confirmed that Ukraine was deploying craft with 'a kill range of 20km' underlining how far the battlefield has become extended beyond the traditional idea of frontline trenches.
On Saturday night, about half a dozen drones, almost certainly Ukrainian, hit a Russian fibre optic factory in Saransk, about 400 miles from the border. A long range drone targeted it again the next day. The Optic Fibre Systems site was described by Baza, a Russian Telegram channel with links to the security services, as the only fibre optic plant in the country, though the level of the damage caused remains unclear.
There are examples of drone operators from earlier this year being able to trace the cables back to the positions from where they were launched and target the enemy crews. But if this technique was a successful one, fibre optic drones would have disappeared as soon as they appeared on the battlefield, when – from presidents to workshops – all the talk is of increasing numbers.
Other means of countering fibre optic drones are emerging. At the simplest level, the increasingly prevalent netting is designed to entangle the drone and its cables. Ukraine is also seeking to devise ways to sever or burn the cables. 'That is the question everybody asks, if it's possible to destroy the cable,' Fedorenko says. 'I will tell you it's very strong, but we are working on it.'