By Dan Peleschuk and Tom Balmforth
KYIV/LONDON, May 19 (Reuters) - From burning oil refineries to a stalling ground offensive, Russia is suffering problems in its war against Ukraine that partly stem from a growing Ukrainian military strength: the use of medium-range drone attacks.
By targeting Russian air defences and logistics dozens of kilometres behind front lines, Ukraine is disrupting Russia's battlefield advances and opening the way for long-range strikes on Russian oil and military facilities,
said two Ukrainian commanders, two drone specialists and three military analysts.
Ukrainian officials say more resources have in recent months been poured into "middle strikes", typically ranging between 30 km (19 miles) and 180 km behind front lines.
This has enabled Ukraine to strike Russian radars, short- and medium-range air defences, communications infrastructure, logistics and large military vehicles at "operational depth", the sources said.
Long-range attack drones can now slip through defences more easily to hit Russian oil facilities far behind front lines, said Robert Brovdi, commander of Ukraine's Unmanned Systems Forces.
"The role of middle strikes is currently decisive," Brovdi told Reuters in a voice message, referring to strikes of up to 2,000 km.
Defence analysts say such attacks alone cannot turn the tide against Russia but that they are having an important impact and the dynamics of the war may be shifting.
In the last few months, Ukrainian long-range drone attacks have caused the most extensive damage to Russian oil infrastructure since Moscow's 2022 invasion.
Last month, Russia reduced oil output because of drone attacks on ports and refineries, and crude oil supplies via Russia's only remaining oil pipeline to Europe were halted, Reuters reported.
The attacks have lifted morale in Ukraine after a winter of Russian attacks on its power network and Russia's rate of battlefield advances is at its slowest since 2023.
SCALING UP
President Volodymyr Zelenskiy said this month the number of Ukrainian "middle strikes" had doubled compared to March, and quadrupled since February.
"Kusto", a field commander in the 7th battalion of Brovdi's 414th Separate Unmanned Systems Brigade, said Ukraine's middle-strike capabilities had grown significantly since the autumn.
"We have scaled up, increased the number of crews, and expanded the number of systems in use. There is also greater diversity in the available platforms," he told Reuters in written remarks.
Kusto said his unit focused mainly on targets up to 100 km from the line of contact. He said Russian radar installations and air-defence systems such as the Buk, Tor and Pantsir were the highest-value targets. Other primary targets were large vehicles and logistics.
"The aircraft (drone) itself typically flies about 150 kilometres from the launch point and then begins searching for targets in the designated area," he said.
Kusto said the most frequently used "middle-strike" drones used by his unit were the domestically produced Chaklun V, followed by the B-2.
Brovdi said manual control, rather than coordinate-based guidance, allowed for better precision, and that no more than three drones were typically spent for each confirmed destruction of a target.
His forces have destroyed at least 129 air-defence systems this year in Russian-occupied areas, he said. Reuters could not verify that figure independently.
Ukraine has carried out multiple strikes on oil facilities in the Russian Black Sea port city of Tuapse, and Brovdi said on Friday his forces had struck the Ryazan oil refinery, one of Russia's largest.
Ukrainian attacks have also forced the suspension of operations at NORSI, Russia's fourth-largest oil refinery, and in Perm, about 1,500 km from the Russia-Ukraine border.
STRETCHING OUT LOGISTICS
The deep strikes have enabled more mid-range attacks by forcing Russia to disperse air defences away from front lines, said Justin Bronk, a senior fellow at the Royal United Services Institute in London (RUSI).
That allows Ukrainian forces to target assets beyond the range of artillery or remotely operated First-Person View drones, such as ammunition and fuel depots, command points, supply vehicles and other mid-range drone teams.
In April, Ukrainian forces conducted over 160 middle strikes at a range of 120-150 km, the Defence Ministry said.
Such attacks hamper Russian battlefield operations by stretching the distance between frontline troops and their supporting forces, said Illia Mashyna, commander of Ukraine's 431st Separate Unmanned Aircraft Systems Battalion "Brodiahy".
"The farther you pull back, the more you complicate logistics," said Mashyna, underlining the importance of careful planning and consistent coordination to having an effect.
The U.S.-based Institute for the Study of War said Russia's battlefield advances had slowed since October, partly because of mid-range strikes but also due to local fortifications and terrain, particularly in the Donbas region.
Russian forces have also faced communications problems since tech billionaire Elon Musk cracked down on their use of the Starlink satellite internet service.
INNOVATING OUT OF NECESSITY
RUSI's Bronk said Kyiv's rapid development of its mid-range capability reflected a gap it had needed to fill, with Russia pressuring Ukraine's outmanned and outgunned forces and also successfully using middle strikes.
Frequent battlefield use has driven rapid innovation as Ukraine tries to strengthen its own defence production and rely less on foreign supplies.
Communication between producers and frontline users means feedback is incorporated into drone systems within days, Kusto said.
A technical engineer in the same unit as Kusto, with the call sign "Symbol", said some manufacturers now deliver platforms that are almost fully combat-ready, requiring no further programming.
"Previously, middle strike was more of a one-off capability," he said in written comments. "Now it's a systematic part of operations."
Emil Kastehelmi, of the Finland-based Black Bird conflict analysis group, said mid-range attacks may not turn the tide against Russia but represent a challenge to which Russian forces must adapt.
"And I don't think we've seen the pinnacle of it yet," he said.
(Writing by Dan Peleschuk; Editing by Timothy Heritage)
