Drones have been used in warfare for decades – pilotless, radio-controlled aircraft were tested as far back as World War One. But the war in Ukraine has seen an explosion in the scale with which they're deployed. They have transformed from performing specialized functions to becoming one of the most important and widely used weapons on the battlefield.

The deployment of smaller drones, which was inconsistent at the beginning of the war, has now become extremely organised, with UAVs now integrated into Ukraine's armed forces structure. Almost every fighting brigade has an assault drone company, while most units have small reconnaissance drones.

The Ukrainian government aims to make a million FPV drones in 2024. To put that into context, it's around double the number of artillery shells supplied by the entire European Union over the past year.

The process of deploying this technology on the battlefield begins with reconnaissance drones equipped with high-spec cameras that transmit real-time video back to their pilot's control screen, allowing the operator to look for enemy targets from above.

Reconnaissance drones come in various shapes and sizes. The most popular is the Chinese-made DJI Mavic, a quadcopter used by civilians all over the world to film landscapes or events like weddings. These drones, which can cost about $1,500 to $3,000 each, are used by soldiers in trenches to survey the battlefield.

Meanwhile, specialist crews further back from the frontline fly larger, often winged reconnaissance drones equipped with cameras that cost thousands of dollars. These craft can fly and see much further into enemy territory.

When targets are spotted, their coordinates are relayed to commanders through secure messengers and entered into Kropyva, a digital map containing aggregated data on Russian targets.

Commanders then determine the best method to strike a particular target. Ukraine has more limited resources than its Russian adversary, so tough decisions often have to be made to conserve scarce munitions.

Because FPV drones are guided to their target, they are far more accurate than most artillery. This allows them to chase and hit moving vehicles which would otherwise have been able to evade shells. However, traditional shells can still deliver a much stronger explosive punch than drones' smaller warheads.

Soldiers have learned to fear the ominous buzz of the drone's propellers overhead, as this often indicates they have either been spotted or are about to be attacked.

The increased use of drones in the war has forced heavy machinery such as tanks to move several kilometres further back from the front line, according to Ukrainian soldiers. Infantrymen, meanwhile, cite FPVs and drones that drop munitions as their biggest threat and say there are now so many in the air that it's difficult to move to and from trenches or reinforce dugouts.

In a long and large conflict, cost is key: the fewer resources used to destroy a target, the better.

FPV drones, as well as their bomb-dropping cousins, hold some significant advantages over most other types of weaponry: An FPV drone can cost less than one artillery shell, and is more accurate.

Drone technology is nonetheless most effective when used in conjunction with other types of weaponry. Even FPV drone pilots who have racked up dozens of hits on enemy targets say they would be almost powerless without infantry and artillery to hold the front line.

Long-range attacks

Drones are not just used on the battlefield: both Ukraine and Russia have hit targets hundreds of kilometres away from the front lines using long-range UAVs.

These long-range drones often hit factories making weapons, military bases or energy facilities deep inside enemy territory.

The widespread use of long-range attack drones began in the autumn of 2022, several months into the war, when Russia bought hundreds of Shahed drones from Iran and began to fly them into Ukrainian targets. They immediately proved to be extremely effective, costing less even than the air defence missiles Ukraine initially used to down them.

The Shahed follows a pre-programmed path. That journey will often include as many twists and turns as possible to confuse and exhaust Ukraine's air defences, which is one of the drone's primary functions for the Russians.

The Shahed-136, the most commonly used model, is estimated to cost $100,000 or less, and Russia has built its own facilities to produce it. Ukraine has had to adapt, deploying flak cannons and machine guns atop pickup trucks to shoot them down.

At the same time, Ukraine has been developing its own drones to strike targets deep inside Russia as a way of making up for its own lack of long-range missiles.

Early incarnations of Ukrainian long-range drones were usually downed by Russian electronic warfare systems, but Ukraine's military appears to have learnt lessons from this and has been able to strike targets deep within Russia in recent months, including factories and oil refineries.

In late January, Russian energy firm Novatek was forced to suspend operations at its huge Ust-Luga fuel processing and shipping terminal for three days after a Ukrainian drone attack started a fire. Operations at the facility, key for the export of some hydrocarbons, appeared to be affected for several weeks.

Electronic warfare against drones

Electronic warfare (EW) systems have proved to be the most effective way of stopping drones. Both sides use EW systems to jam radio frequencies in certain areas. When a drone's signal is jammed, the pilot loses the ability to control the craft or can no longer see the video signal, depending on which frequency has been disrupted.

EW is becoming increasingly dense on the front lines, according to Ukrainian pilots. Most EW systems have a limited span of frequencies, so drone pilots have responded by switching to less commonly used ones. This leads to a technological game of cat and mouse on the front lines, as EW operators seek to disrupt drones flying on constantly-shifting frequencies.

Both sides also have to contend with electronic reconnaissance systems, which can trace drones’ signals back to enemy pilots, potentially identifying their location.

Pilots have responded to this by increasing their use of signal repeaters, which act as an intermediary station for the connection between craft and pilot. Repeaters can be deployed on the ground or attached to another drone and flown in the air, increasing signal range and obscuring the pilots' positions.

While large, truck-mounted EW systems are used to protect expensive equipment, infantry units have started using smaller systems to protect their trenches - though the effectiveness of the less powerful ones can be patchy.

Serhiy, a Ukrainian infantry platoon commander from the 59th Brigade fighting in the east of the country, said his unit's homemade EW system, as well as their portable EW devices or "drone guns", had become less effective due to Russian UAVs changing frequencies. He declined to give his full name as Ukrainian soldiers are told not to divulge their identities for their safety.

Next-generation drones with AI

In response to the increasing challenges posed by EW systems, both Ukraine and Russia are racing to develop drones guided by artificial intelligence. These drones identify and lock onto their targets without the need for communication with their pilot, making them impervious to signal jamming.

AI target identification is already being used by both sides in a small number of drones.

"You cannot jam such a drone, because there is nothing to jam," said a 20-year-old Ukrainian drone pilot from the 92nd brigade who goes by his call sign Darwin. Ukrainian drone industry figures say the technology still needs to be developed further before it can be widely used.

Nevertheless, many manufacturers, politicians and pilots say they believe AI systems could be at the heart of drone warfare in the future. Some predict that EW protection could become so widely used as to render most conventional FPV drones useless.