The leaked memo says the U.S. government’s ban on Chinese drones has made it harder to put out wildfires.

Last year, the U.S. Department of the Interior, which maintains federal land, announced that its drone squad had been temporarily grounded over concerns that it might be used for espionage,media The Verge reported. Now, an internal memo leaked to the Financial Times says the decision hampers the federal government’s ability to put out wildfires.

The leaked memo says the U.S. government's ban on Chinese drones has made it harder to put out wildfires.

The suspension of the UAV aircraft has led to an de facto ban on the purchase of Chinese drones and drones containing Chinese components. That led the Home Office to cancel plans to buy 17 Iignis drones, according to the Financial Times. These are professional drones used to start fire suppression and are key tools for controlling wildfires.

The leaked memo says that without drones, the department would have been forced to use man-driven aircraft to fight fires. An internal analysis by the department found that by the end of the year it would have carried out only 28 per cent of controlled combustion, which it plans to use with a new drone squad.

” (The department’s current aircraft force) must be expanded to meet the required preventive measures to reduce wildfires by reducing vegetation,” the memo said, according to the Financial Times. “Refusal to purchase UAS (drone) aerial fire extinguishers directly transfers the risk to firefighters, who must use human-piloted aircraft to accomplish these tasks, rather than taking advantage of UAS as a safer option.”

According to the Financial Times, the internal memo was written earlier this year by the department’s Air Services Office. The publication also notes that while the United States is facing one of the worst wildfire seasons to date, no outbreaks have yet broken out on federal land.

The initial decision to ground the Interior Department’s aircraft was part of the Trump administration’s broader effort to limit Chinese technology. In particular, the drone market is dominated by Chinese manufacturer Daji, which said when news of the suspension broke last year that its drones were not using only U.S. parts. The agency uses drones not only to control wildfires, but also to survey land and dams to monitor endangered wildlife.

Interior Secretary David Bernhardt said last year that the department’s aircraft would be grounded until a full safety review could be conducted. Bernhardt noted that drones can still be dispatched in emergencies, including natural disasters, but that rule does not appear to extend to the purchase of new hardware. In January, the agency reiterated its suspension, but it was unclear what progress had been made in the security review.