Ukraine’s 58th Separate Motorized Infantry Brigade recently destroyed two bridges inside Russia’s Belgorod region in a strike that highlights the growing impact of low-cost, first-person-view (FPV) drones on the modern battlefield. Hiding under the two structures were stockpiles of Russian mines and ammunition near the border with Ukraine’s Kharkiv region.

The 58th Brigade said in a statement that the bridges were mined by the Russian military and used as a supply route for its forces in the area. Ukrainian officials added that the structures themselves were booby-trapped and prepared for demolition in case of a Ukrainian breakthrough.

“Such successful work on undermining the bridges has been going on in the border villages of our area for some time,” a representative of the 58th Brigade told CNN. “It became clear that something was going on there.”

In an act of “retaliatory damage,” as one of its members put it, the unit deployed an FPV drone equipped with fiber optics to surveil the bridge and investigate the Russians’ activity. The drone, which was able to navigate under the bridge without losing signal, discovered a large cache of anti-tank mines and other ammunition.

“We saw the mines, and we struck,” the brigade representative said.

Both the unit’s video footage and a second camera placed near the bridge captured the aftermath of the explosion. Russian forces had planned the strike well, building a vast bomb shelter underneath the bridge and covering the ammunition caches with dirt and plywood.

CNN geolocated the bridge to Belgorod, which borders Ukraine’s Kharkiv region.

The Unit Smuggled in Drones

Buoyed by its success, the brigade then targeted another bridge in the area. The new attack, which was filmed in the same way, also turned up a stockpile of mines hidden under the other structure. A second drone was smuggled in to find the ammunition and blow it up, again with devastating effect.

“(We) saw an opportunity and took it,” the unit said, according to a translation by CNN. Both drones have been destroyed and their loss written off as an act of revenge for damage Ukraine has taken since the start of the war.

Critics have focused on the low cost of these strikes, which were made with drones that cost between 25,000 and 30,000 Ukrainian hryvnias each, or roughly $600–$725. For comparison, Kyiv has previously used more expensive U.S.-supplied HIMARS systems to target Russian infrastructure in the Kursk region. A single HIMARS rocket costs tens of thousands of dollars, while the launchers themselves sell for millions of dollars apiece.

Ukraine’s commanders have preferred to use more costly munitions in those cases because the drones would have struggled to navigate to targets so far inside Russia’s territory. But low-cost drones, often cobbled together using commercial parts and modified by volunteers, have given Ukraine another option for attacking deeper inside Russian territory.

Cost-Effective Assaults

Ukrainian FPV drones have become an important and cost-effective tool in this regard. In June, for example, the Air Force and volunteers in the country’s paramilitary Territorial Defense Forces smuggled in drones close to Russian airfields to destroy or damage dozens of aircraft.

In June and July, this drone campaign played a major role in repelling Russia’s large-scale attempt to cross the Siversky Donets River in the Luhansk region, where they ultimately failed to capture Bakhmut and spent more than a month “bleeding out.”

“The value of these drones cannot be overstated,” a representative of the 58th Brigade said. “They allow us to achieve results that would otherwise require weapons we don’t have.”

Ukraine Fighting Against Russian Attacks

The news of the destroyed bridges offered a rare positive development in what has otherwise been a difficult period for Ukraine. Fighting has intensified along the frontlines in recent weeks, with Russian forces slowly grinding forward in eastern Ukraine. Moscow has also redoubled its near-daily missile and drone attacks on Ukrainian cities, with Kharkiv being the latest target in recent days.

The Russian Defense Ministry has touted its so-called Cross-Continental Ballistic Missile (ICBM) strikes on Kyiv as a major escalation in recent months. Although Kyiv has disputed that the new ICBMs are a gamechanger, the intensifying pressure on the battlefield and the stepped-up missile attacks on Ukrainian cities have taken their toll.

Ukrainian officials have become even more adamant in recent days that Kyiv should not agree to any ceasefire without Putin backing down from his demands for a wider land grab that would hand over major parts of the country. Putin has given no indication he will do that, however, and instead has announced plans to continue his offensive.

Analysts say it is unlikely Russia’s retreat from Kharkiv and northern Ukraine in the early months of the war has emboldened Kyiv into a widespread attack on Russian territory. Putin’s pledge to use whatever weapons he has to stop Kyiv from retaking Russian-occupied Ukraine is unlikely to have made Ukrainian officials any more confident about a large-scale advance, they say.