Over the pitch-black fields of central France, a drone arcs into the night sky, its infrared camera scanning a railway line below. The mission: deter thieves who strip copper cables from train tracks -- a crime that costs millions and disrupts traffic.
To tackle the chaos caused by the incessant theft of cables running along its 28,000 kilometres (17,400 miles) of railway tracks, France's national rail operator SNCF deploys drones similar to those now used to survey frontlines in war-torn Ukraine.
Copper -- nicknamed "red gold" -- is prized on the black market, now fetching close to 10,000 euros ($11,500) a ton.
Criminal networks cut and haul away kilometres of wiring, reselling it for hefty profits.
French start-up Delair supplies SNCF's fleet of 200 drones and sells to the Ukrainian military as well.
During a recent nighttime demonstration in Artenay, around 80 kilometres (50 miles) south of Paris, a drone launched carrying two cameras, one infrared, to be eyes in the night.
"This allows for continuous data collection across the entire network, 24 hours a day, seven days a week," said Alexis Meneses, strategy director at Altametris, an SNCF subsidiary that manages drones.
Launched in 2017, the rail group now deploys drones for nearly 2,000 flights a year to check the condition of railway infrastructure, with 200 dedicated solely to security.
On the ground in Artenay, a worker spots glowing two-legged figures on a control screen. They are near the rails, moving towards an abandoned station.
When people are spotted near the tracks, railway police are dispatched and most often only find employees working on the lines, but sometimes, they send a thief running.
"Deterrence is the main goal," said Olivier Bancel, general manager of customer operations at SNCF Reseau, which manages infrastructure.
Since September, four cable theft gangs have been neutralised and one caught red-handed, said Christophe Bouteille, deputy director of security for the SNCF group.
Thefts have decreased from 15 years ago, according to Bouteille, when SNCF recorded some 3,350 metal thefts, resulting in a loss of 30 million euros and over 5,800 hours of train delays.
SNCF no longer discloses figures but says it invests 100 million euros ($115 million) per year to monitor its railway tracks, of which 20 million is dedicated solely to security operations.
Across industries targeted by metal theft, the interior ministry recorded around 2,100 copper thefts in 2024 outside of major urban centres, and over 200 perpetrators were arrested between January 2023 and October 2024.