The cyberattack targeting French supermarket freezers and causing millions of dollars in losses last week should be an ominous warning to American businesses, cybersecurity experts told Fox News Digital.

Unknown hackers took over the refrigeration in hundreds of supermarkets across France, raising temperatures above 100 degrees Fahrenheit overnight, causing massive spoilage. It could happen here, and it isn't just grocery stores that need to be on guard, John Walsh, senior vice president at the Germany-based software company IGEL, told Fox News Digital.

"Think about if we don't have water for seven days, or if they attack freezers and we don't have food," Walsh said. "That's a tough situation for people to live through, and it could create a lot of economic and social unrest. We're seeing that we're vulnerable and that attacks are taking systems down." At IGEL, Walsh works with governments and companies who build and deploy critical infrastructure — such as Siemens and Rockwell — to bolster their operational security.

As was the case in France, where Danish commercial refrigeration system manufacturer Danfoss highlighted that many of its affected fridges were legacy systems that no longer receive updates, much of the U.S.’s critical infrastructure is also in need of retooling, Walsh said.

"A primary obstacle in [operational technology] environments — whether in food manufacturing, pharmaceuticals, oil, or utilities — is that facilities operate assets that are 15 to 20 years old," Walsh said. "These systems are expensive, fragile, and essential to ongoing operations." Decision makers at the companies Walsh works with don’t want to go through the hassle of taking key systems offline in order to upgrade and secure them further, operating under a "if it's not broken, don't fix it" mindset," he said.

But critical infrastructure, like almost every aspect of American society, is becoming increasingly integrated with technology and embedded into digital infrastructure, forcing cybersecurity firms to fundamentally shift strategies.

"One of the big things we have to consider is that we're moving from a thought process of security to resilience," Walsh said.

As AI helps hackers become more sophisticated, it’s no longer wise to attempt to completely shut them out of key systems, Walsh said. System operators are better off assuming the hackers are already there.

"Security is kind of like, 'I feel I can trust that things are okay.' Resilience is where you make the assumption the attacker is present—where, when the attacker is present, you control the blast radius," Walsh said.

A so-called Trojan horse could already be inside America's electrical grid and other critical infrastructure, just waiting for the adversary to activate it, he said.

"They've demonstrated taking it down, which to some degree is them practicing, honing their skills, and honing their methodologies against real targets while sending a message," Walsh said.

Policy experts are grappling with how to make recommendations to lawmakers, given that so many things we depend on in our everyday lives are connected to the internet.

"I am shocked that appliances have access to the internet," Amy Kremer, the chair of Humans First, told Fox News Digital.

"I understand the convenience, but at the same time, you are going to have potential problems with it. That should be a concern to all Americans — not just appliances, but things like your Nest thermostat and other devices in your house that could be hacked into," she continued.

"As we learn every single day, it's capable of more and more. It's great that we have technology — it's changed the world and made it a much smaller place where we interact and communicate with each other all the time. But with that also comes vulnerabilities," Kremer added.

America’s critical infrastructure is indeed vulnerable to these types of threats, Walsh said, citing previous examples, including a 2026 coordinated cyberattack on Minnesota’s water systems.

"Think about if you were to try to disrupt the U.S. economy or begin to do terrorism-type activities. What would you do? You'd go after water and wastewater.

You'd go after the food supply. Exactly what occurred here, but at a larger scale," Walsh said. "We're definitely more vulnerable, they're definitely targeting us, and citizens, government, and the international community need to get governance in place to push industries to implement these protections," he said.

Walsh also warned that this could be just the beginning, claiming a recent string of hacks could be indicative of hackers honing their skill sets as they prepare for bolder attacks.

"I do think that what we're beginning to see is a pattern across the U.S., France, and the UK. We see the adversary—potentially a geopolitical adversary—basically practicing their art and demonstrating their art in different locations," he warned. Fox News Digital contacted Danfoss for further comment.