The Pentagon is investigating unexplained refrigeration failures at several U.S. military bases as a suspected cyberattack, following incidents in August that spoiled food at military commissaries. The investigation comes amid a separate confirmed cyberattack on supermarket refrigeration systems in France, where attackers remotely manipulated temperature controls at hundreds of stores.

According to an October 29 Reuters investigation citing four officials familiar with the matter, at least six U.S. military commissaries experienced refrigeration malfunctions in late August. At Fort Huachuca in Arizona, freezer equipment unexpectedly entered defrost mode overnight, raising temperatures and leaving food spoiled by morning.

U.S. military cyber investigators are coordinating with French authorities. The Pentagon confirmed that a unit of U.S. Cyber Command was working with law enforcement and other government agencies. The Army Criminal Investigation Division said its Cyber Field Office was also involved and was cooperating with French investigators examining similar refrigeration disruptions in Europe.

The investigation has not established whether the U.S. incidents resulted from malicious activity. Officials have not identified a suspect, disclosed a method of intrusion, or confirmed any connection between the American and French incidents.

The French attacks affected more than 350 commercial establishments. During October, attackers remotely altered refrigeration controls at supermarkets across France, causing widespread food spoilage and, in some cases, equipment overheating and fires. The incidents affected major retail chains and generated losses potentially reaching tens of millions of euros.

Many affected French refrigeration systems used controllers manufactured by Denmark’s Danfoss. The company acknowledged that numerous devices were obsolete or operating outdated firmware, conditions that could have made unauthorized access easier. Earlier reporting by Le Monde described attackers manipulating defrost cycles and temperature settings rather than simply disabling cooling equipment.

Reuters could not establish which refrigeration controllers were installed at the affected American bases, leaving the technical relationship between the incidents unresolved.

Internet-connected industrial controls are central to the security concerns. Refrigeration controllers originally designed for isolated, on-site operation are increasingly accessible through networks for remote monitoring and maintenance. When such operational-technology systems are exposed to the Internet, outdated software or inadequate access controls can provide opportunities for unauthorized manipulation.

The consequences extend beyond ordinary computer-system disruption. Compromised refrigeration controls can alter physical operating conditions, destroy temperature-sensitive inventories, damage equipment, and interrupt food distribution.

The incidents illustrate how Internet connectivity in building-management and industrial-control systems can create cybersecurity risks with direct physical consequences, even where the equipment was never originally designed for remote access.