On September 15, Ukraine’s 58th Separate Motorized Infantry Brigade destroyed two bridges in Russia’s Belgorod region in a rare strike deep inside Russian territory. The operation, which used commercially available first-person-view (FPV) drones to identify and then detonate Russian ammunition stores hidden beneath the bridges, marked one of the latest examples of how cheap drones are changing the face of modern warfare.

The two bridges, located close to the border with Ukraine’s Kharkiv region, were being used by Russia to transport mines and ammunition to its forces near the frontline, according to Ukrainian officials. The Russian military had even mined the bridges in preparation for a potential Ukrainian attack. But Ukrainian forces appear to have used a similar tactic to turn that minefield against Moscow.

The Ukrainian 58th Brigade said it first noticed suspicious activity at the scene and then began searching the area with an FPV drone equipped with fiber optics that could fly inside the structure without losing signal. The drone discovered a large cache of Russian anti-tank mines and other ammunition concealed beneath the bridge. “We saw the mines, and we struck,” a brigade representative told CNN.

The Ukrainian drone then detonated in a huge explosion, destroying the ammunition. A second camera captured the blast from further away. Ukrainian officials have geolocated the bridge as part of Russia’s Belgorod region, which shares a border with Ukraine’s Kharkiv region.

The unit then searched another bridge and discovered it had also been mined. A second drone was then deployed, triggering another powerful blast. “(We) saw an opportunity and took it,” the brigade said in a statement.

Expensive Guided Missiles vs. FPV Drones

Destroying two bridges inside Russian territory under normal circumstances would usually require the use of guided missiles or precision-guided bombs, which Ukraine has limited supplies of, most of which have been provided by Western partners. For example, Ukraine has used U.S.-supplied HIMARS multiple rocket launchers in the past to target bridges and other infrastructure in Russia’s Kursk region. Each HIMARS launcher costs millions of dollars and the individual rockets cost tens of thousands each.

In comparison, Ukraine’s 58th Brigade has said that the drones that it used to carry out the Belgorod operation cost between 25,000 and 30,000 Ukrainian hryvnias each, or around $600-$725. This is cheaper than most smartphones. But the strike is still significant. Drones like the ones Ukraine used to destroy the Belgorod bridges are difficult to intercept. They have been extensively used in Ukraine in recent years, particularly by Russia, which used small drones to attack Ukrainian cities.

Kyiv has since improved its defenses, including installing detection sensors along the border and making use of commercial technology from companies like SpaceX. Moscow is also suspected of using commercial technology in Ukraine, including alleged Chinese FPV drones that have been captured in Ukraine.

FPV drones have already played a growing role in the Ukraine war. In June, Kyiv used drones smuggled close to Russian military airfields to destroy or damage dozens of aircraft. According to military analyst Mykola Bielieskov, this latest operation is yet another example of Ukraine creatively using “modest technologies to achieve outsized effects.”

The Battles in Kharkiv

The destruction of the bridges in Russia’s Belgorod region, where they were being used by Russia to supply ammunition and other supplies to its forces in Kharkiv, comes as Ukraine’s forces are facing growing pressure along the frontline. Russian forces have been grinding forward in eastern Ukraine, while Moscow continues its campaign of near-daily missile and drone strikes on cities and infrastructure across the country.

The strikes also come as Russian President Vladimir Putin has been rebuffing offers of a ceasefire and announced that Moscow would be continuing its offensive in Ukraine. Against this backdrop, the images of two bridges in Russia destroyed by Ukrainian drones offered a rare boost for Kyiv.

Russia has yet to officially acknowledge the strike, although the loss of the bridges will make it harder for Russia to transport supplies and ammunition to its forces in Belgorod, which share a border with Ukraine’s Kharkiv region. Russian-backed militants have been active in the area, where they have previously carried out attacks on Ukrainian positions.

“The simple fact that they were able to do it shows that they had time and space to conduct innovative activities,” Bielieskov said of Ukraine’s 58th Brigade. The operation is just one example of a wider reality for Kyiv, according to the military analyst: Ukraine must innovate to survive. Facing a larger and better-supplied Russian force, Ukraine has had to make use of its limited resources and improvise, which in this case, has involved using commercial drones and modifying them for military purposes.

“The value of these drones is priceless. They help us to achieve goals that otherwise would be inaccessible to us, for example, due to the lack of weapons,” the 58th Brigade representative said.