French officials on Monday accused Iran’s Revolutionary Guards of responsibility for the cyberattacks that knocked out commercial refrigerators and freezers across France last month, saying there would be consequences for Iran.

The hacks that struck hundreds of French supermarkets in early October were among the most disruptive cyberattacks of the Iran war that began in February, a conflict that has been marked by scattered incidents of alleged digital disruption. These have included hacks against the Los Angeles transit system in March, against US water treatment plants in July and against ships bound for the United States in August.

Iran’s mission to the United Nations did not return messages seeking comment. Iran routinely denies carrying out malicious cyber operations.

The French announcement was made only minutes after Reuters revealed that investigators privately suspected Iran of being behind the attacks. French Foreign Minister Jean-Noel Barrot said the Iranian ambassador had been summoned to France’s foreign ministry. Barrot also threatened further EU sanctions against Iran.

The Oct 11 cyberattack, which overrode the temperature controls on commercial fridges in hundreds of establishments, appeared to have been easy to pull off, cybersecurity experts previously told Reuters. The firm behind many of the stricken units said that several were obsolete or were running outdated firmware, which could have made it easy for hackers to break in.

The effects were still dramatic. Some refrigerators had the temperature turned up so high they caught fire. In the hours following the hack, supermarket employees carted boxes full of perished meat and melted ice cream into giant trash containers. The attack’s total costs could add up to tens of millions of euros nationwide, one French supermarket owner estimated.

Reuters could not establish exactly how the French made their determination.

The October hacks were followed this month by a second wave of hacking that hit more than 100 establishments across Europe and even affected refrigerators used by French blood banks, prompting employees there to have to move some of the blood to different cold storage units.

The seemingly straightforward nature of the refrigerator hacks and their repetition across multiple countries prompted speculation about who might be responsible amid ongoing concerns over Russia’s suspected sabotage campaign in Europe, the war between the US and Iran and the global rise of AI-powered cyberattacks.

US refrigerator attacks

The sabotage of European supermarket fridges was preceded by at least one similar incident in the United States.

In August, refrigerators in at least half a dozen military commissaries went out of commission. Pentagon investigators are treating the malfunctions as a suspected cyberattack and are working with French officials to get to the bottom of what happened, Reuters reported last month.

Reuters could not independently establish whether there was any link between the refrigeration incidents at US military bases in August, the hacking campaign in France and the more recent wave of refrigeration hacks that struck Europe.

A person familiar with the matter said that the Pentagon considers Iran a suspect in the August commissary hacks but that the investigation is still in progress.

Reuters could not establish how the military made its determination or whether it was also looking into other suspects. That the US military considers Iran a suspect in the commissary sabotage campaign was first reported last month by news website Nextgov.

The Pentagon said on Monday that it is “aware of speculation regarding a potential cyber incident” but that military investigators were on the case and it could not offer further comment for security reasons.