EXPLAINER: How have drones changed warfare in 2025?

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, with thousands of unmanned aerial vehicles (UAVs) used to track enemy forces, guide artillery and bomb targets.

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.

Romanian and German NATO fighter jets were scrambled on November 25 near Romania's border with Ukraine to respond to a drone incursion that penetrated deeper than ever into Romanian airspace, in what Bucharest called a Russian provocation.

Drone fragments without an explosive charge were later found on Romanian territory.

Tuesday's breach was the 13th that Romania has reported into its airspace since Russia's 2022 full-scale invasion of Ukraine. In addition to being the deepest, it was also the first to take place during daylight, rather than at night.

European Commission President Ursula von der Leyen has said it was time for Europe to build a "drone wall" to protect its eastern flank.

Drone incidents over airports in Denmark and Germany in 2025 reinforced European leaders’ view that the continent urgently needs better protection against such threats.

Russia's drone incursions and airspace violation of European NATO countries has increased since September, when more than 20 Russian drones entered Polish airspace and three Russian military jets violated Estonia's airspace for 12 minutes.

Since then, many drone flights, the origin of which are mostly unknown, have disrupted airspace operations in Europe.

NATO deployed F-35 and F-16 fighter jets, helicopters and a Patriot air defence system collectively worth billions of dollars to respond to Russian Gerbera drones - based on Iranian Shahed models – that cost a tiny fraction of the price.

FPV drones

The tiny, inexpensive FPV (first-person view) drone has proved to be one of the most potent weapons in this war, where conventional warplanes are relatively rare because of a dense concentration of anti-aircraft systems near front lines.

FPVs - originally designed for civilian racers - are controlled by pilots on the ground and often crash into targets, laden with explosives.

The total cost of the drone’s components, including an explosive warhead secured with cable ties, can be as little as $500 or less.

The FPV drones take off from improvised platforms several kilometres from the front line. Depending on their size, battery and payload, range varies from 5 km to 20 km or more. A soldier operates the drone using a remote controller and a headset that allows them to see the view from the camera. Meanwhile, another soldier looks at a tablet computer with maps and gives directions.

After flying across the front line, the pilot spots the target: a tank. They will select one of its most vulnerable parts - an open hatch, the engine or ammunition stored in the turret.

Usually, the target will already have been detected by a reconnaissance drone and the FPV would zip straight to its location and fly at high speed into the target.

FPV drones 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.

DRONE INCURSIONS

BELGIUM

The Brussels and Liege airports were closed on November 4 evening after drones were spotted, diverting many incoming planes and preventing others from taking off. The Brussels airport reopened Wednesday morning though some flights were cancelled and others delayed.

CZECH REPUBLIC

The Czech army said on September 10 it was detecting an increasing number of unidentified drones flying over its military facilities, according to the Institute for the Study of War research group.

DENMARK

Drones disrupted air traffic at six Danish airports in September, including in Copenhagen, the Nordic region's busiest airport, in what Prime Minister Mette Frederiksen called a hybrid attack on her nation.

ESTONIA

Three Russian military jets violated NATO member Estonia's airspace for 12 minutes on September 19, before NATO Italian fighter jets escorted them out.

GERMANY

The Berlin and Bremen airports briefly closed on the weekend after two separate drone sightings, local media reported.

Drones were spotted at airports and military installations across Germany earlier in October, Bild newspaper quoted a confidential police report as saying, suggesting sightings at Munich Airport on October 3 were the tip

LITHUANIA

NATO member Lithuania closed Vilnius Airport and Belarus border crossings on October 28, after several objects, identified as likely helium balloons, entered its airspace, the National Crisis Management Centre said, the fourth such incident in a week.

The country said on October 23 that two Russian military aircraft had entered its airspace for about 18 seconds, prompting a formal protest and a reaction from NATO forces, while Russia denied the incident.

NORWAY

Norway's Oslo Airport temporarily paused one or several landings early on October 6 after a report of a drone sighting near the airport, its operator Avinor said.

POLAND

Polish MiG-29 fighter aircraft intercepted a Russian reconnaissance plane over the Baltic Sea on October 30, Polish Defence Minister Wladyslaw Kosiniak-Kamysz said.

The country's army said that its jets had intercepted a Russian aircraft flying a reconnaissance mission in international airspace over the Baltic Sea on October 28.

Some 20 Russian drones entered the country's airspace on the night of September 9-10. NATO deployed F-35 and F-16 fighter jets, helicopters and a Patriot air defence system to respond to the incursion.

ROMANIA

Romania scrambled fighter jets on September 13, when a drone breached the country's airspace during a Russian attack on Ukrainian infrastructure near the border, the defence ministry said.

SPAIN

Flight operations at Palma de Mallorca Airport were temporarily suspended on October 20 following drone sightings, according to the ISW

Changes in warfare

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.

Electronic warfare against drones

Electronic warfare (EW) systems have proved to be the most effective way of stopping drones and are used 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.

Warring sides 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.

Underwater drones

Two European governments have agreed to buy underwater drones for military use, their German manufacturer told Reuters in November , as countries in the region ramp up defence spending to address what they say is an increased Russian threat.

Autonomous underwater drones lend themselves to various military uses, from monitoring undersea cables, tracking submarine activity and looking for mines, specialists say.

But they can be expensive, potentially costing millions of dollars each, while operating underwater for long periods of time is technically challenging.

The Greyshark is a mid-sized, long-range autonomous underwater drone that can be used in groups. Euroatlas says its current model has a maximum time limit of 5.5 days, and that it is working on a model that can spend 16 weeks underwater.

Naval drones have featured in the Ukraine-Russia war, particularly those which travel on the water's surface.

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.

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.

Production: Zainab Elhaj, Oliver Denzer, Leon Malherbe and Mariano Zafra/Reuters