KYIV -- As Russian forces have intensified their advances in eastern Ukraine in recent weeks, they're being helped by a new tool on the battlefield: drones that fly with the use of fiber-optic cables.
"The use of fiber-optic FPV drones definitely creates new challenges on the battlefield," said a border guard with the Pomsta Brigade who goes by the call sign "Phoenix." RFE/RL agreed to identify him and other soldiers by their call signs or first names for this story, according to rules set by the Ukrainian military.
Unlike standard FPV (first-person view) drones -- the term used for drones piloted through a video feed wirelessly transmitted to a pilot's headset, mobile device, or other displays -- the use of fiber-optic cables allows drones to operate without radio signals. This makes them less vulnerable to electronic jamming as they stay directly connected to their operators through up to 15 kilometers of thin coils of fiber-optic cable that resembles a fishing line.
While Ukrainian forces are grappling with declining Western arms support and Russia's manpower advantage, the modified drones represent a shift in battlefield tactics in Ukraine. Both Kyiv and Moscow are ramping up fighting as they enter a pivotal stage of the war ahead of U.S. President-elect Donald Trump -- who has vowed to quickly end the war -- returning to office on January 20.
The new drones have reportedly been in use since the summer, but Ukrainian soldiers stationed across the country tell RFE/RL they are becoming a staple of Moscow's battlefield strategy as it pushes for more territory in Ukraine's east.
'A Very Dangerous Weapon'
Many said that, in addition to being used for reconnaissance, they are being increasingly used by Russian troops as self-destructing drones with a small payload attached to target Ukrainian positions and vehicles.
"This is a very dangerous weapon. It's like a brick with a propeller flying at you, and there is little you can do about it," said "Varan," an officer in the 148th Artillery Brigade.
Faced with changing tactics, soldiers say they've been forced to adapt quickly -- with mixed results.
Kostyantyn, a commander of the battalion of the National Guard's Bureviy Brigade, says the ineffectiveness of electronic jamming against the new drones allows them to push farther into Ukrainian lines and fly or reach targets with more accuracy compared to traditional FPV drones.
"This allows them to see our positions better, strike more accurately, and fly longer distances. This makes the situation a little more complicated," he said.
These complications led Kyrylo Budanov, head of the Main Intelligence Agency of Ukraine's Defense Ministry, to call the new drones "a huge problem for us" during a December 31 broadcast by Ukrainian media.
On January 8, the Institute for the Study of War (ISW) noted that Russia is increasingly deploying fiber-optic drones as part of its current offensive and said the drones have carried out a series of new strikes along the front lines.
"There is only a small box where the fiber-optic cable from the drone itself is placed, and it's very easy to miss this because it's the size of a pack of cigarettes," he said.
Not Without Drawbacks
"Medoid," a Ukrainian border guard, says the biggest lesson he's learned from dealing with the drones is the need to take extra precautions and better camouflage potential targets and personnel.
The fiber-optic drones are not without their drawbacks, he adds, saying they struggle in terrain and spaces that aren't open and that he's seen several caught up in tree branches. The drones are also limited in the distances they can cover and where they can strike based on the cable's range.
Given these obstacles, soldiers say the easiest way to take out the tethered drones is with small arms fire. Others say they've deployed large nets -- even fishing nets — to take them out. The cables can be manually severed, but doing so risks exposing soldiers to incoming fire.
But in a war where every advance could prove crucial, the new drones are having an impact on the battlefield.
Russia is reportedly ramping up production of the fiber-optic drones and Ukraine is also looking to develop its own versions, including a model showcased by the Ukrainian Defense Ministry earlier this month.
"For now, we are still in the testing phase," Lyutiy said. "We all see these flashy ads with promises, but in practice, we are only beginning to develop in this direction."
