South Africa is turning to drones and helicopters to fight cable theft that’s disrupting a key export line carrying iron ore from mines owned by Anglo American Plc.

Kumba Iron Ore Ltd. expects to ship 36 million to 38 million tons of the steelmaking ingredient this year, 1 million tons below the upper and lower limits of its previous forecast range. That’s because of a “deteriorating” service on the 861-kilometer (535-mile) rail link that’s used to haul iron ore from its mines to the port of Saldanha on the country’s west coast. 

While derailments have long been a problem on the railway – operated by state-owned Transnet SOC Ltd. — power cable theft is a new and “serious concern,” according to Kumba Chief Executive Officer Mpumi Zikalala. The company is working with police, Transnet and President Cyril Ramaphosa’s National Logistics Crisis Committee to address the issue, she said. 

With the help of drones and other surveillance measures, Zikalala said police were able to make some arrests following a spate of theft in June.

“We’ve strengthened security on the line,” the CEO said in an interview on Tuesday. 

The security issues have led to a buildup of stockpiles at Kumba’s mines. Earlier this year, Transnet rejected Kumba’s overture to take over the running of the iron-ore rail line, which is one of its most profitable but battles to move sufficient volumes.

Kumba, almost 70% owned by Anglo, reported first-half net income of 9.6 billion rand ($536.9 million), down 17% from a year earlier.

In May, capacity on another key corridor that runs from the Port of Durban on the east coast to City Deep in downtown Johannesburg was cut after overhead power lines that keep the trains running were severed. Vandalism on the corridors compounds other problems that Transnet is grappling with, including a shortage of locomotive spare parts on its network that moves coal.