Four officials briefed to Reuters said the Pentagon suspects possible hacking behind mysterious freezer disruptions at U.S. military bases in early September, which led to food spoiling.

One of those officials said military investigators are in contact with their French counterparts about a similar cyberattack on commercial freezers in France.

An investigation by Reuters found that at least six on-base stores were affected. In one case, the freezers did not stop working; rather, their temperatures were raised overnight. Fort Huachuca’s base account in Arizona wrote that the freezers “went into defrost mode and warmed all the food.”

The Pentagon said one of its cyber command units is working with other entities and the police, and the Army Criminal Investigation Division confirmed it is cooperating with French police.

The French attack involved more than 350 stores, and its damage is estimated at tens of millions of euros.