Cyberattacks , bomb threats against passenger flights, civil unrest and suspected acts of sabotage across Europe have raised questions about the continent's resilience — and how prepared it is to defend itself against modern security threats.
Hackers remotely manipulated refrigeration systems at supermarkets across Europe last week, forcing retailers to discard spoiled food and exposing vulnerabilities in everyday infrastructure.
French blood-bank refrigeration systems were subsequently targeted in what appeared to be a similar incident, while a wave of suspected hoax bomb threats disrupted dozens of flights across the continent, forcing diversions and, in some cases, fighter jet escorts.
The week culminated with bomb threats targeting European news outlets, including the U.K.'s Sky News and Irish public broadcaster RTÉ.
The incidents come against a backdrop of heightened geopolitical tensions and domestic unrest across parts of Europe, with civilian infrastructure potentially becoming an increasingly attractive target for hostile actors.
While authorities have not established who was behind the attacks or whether they were connected, defense and security experts warn that disruption to everyday services can have consequences far beyond the immediate economic damage.
If Russia were responsible, such attacks could be intended to demonstrate the costs of Europe's continued support for Ukraine, said Sidharth Kaushal, a research fellow at the Royal United Services Institute, or RUSI.
"I think it's more about cost imposition," Kaushal told CNBC. "Convincing the European political leadership that the costs of a war can come home to them."
Russia didn't immediately respond to a CNBC request for comment.
On Monday, supermarkets in Belgium, Luxembourg, Sweden and the Netherlands found that refrigeration systems had been set to as much as 50 degrees Celsius, or 122 degrees Fahrenheit, affecting retailers including Ahold Delhaize , IKEA, Colruyt Group and Carrefour.
It followed an October cyberattack that targeted hundreds of French supermarkets , causing fires, fridges to overheat and food to spoil. The incidents highlighted vulnerabilities in food-supply infrastructure.
They also highlight the role of private companies in national resilience, as internet-connected equipment can be exploited to cause physical disruption.
Fredrik Blix, cybersecurity expert at Visente and associate professor at Stockholm University, told CNBC that the supermarket attacks required very little technical sophistication since vulnerable refrigeration control systems were connected directly to the public internet, allowing potential attackers to find and exploit them.
"These attacks, they don't really require any specific advanced knowledge to carry out," he said, adding that some systems were protected only by default passwords or easily guessed credentials.
"This is why this is so cheap to do," Blix said, warning that the publicity surrounding the incidents could encourage copycat attacks. "Anyone can do it, and it does not require any resources from a country or anything like that."
Cyberattacks have become more common over the past decade as societies have become more digital and vulnerable systems have become easier to access, Blix said. However, he noted that mounting geopolitical tensions have also made European countries more alert to potential hybrid warfare threats, leading to scrutiny by both governments and media.
While Blix acknowledged the possibility of a state or state-backed actor being behind the attacks, he said the more likely scenario is someone testing the boundaries and "having some fun."
Kaushal said the incidents should be viewed within the larger context of suspected sabotage and hybrid threats across Europe, including damage to undersea cables in the Baltic Sea.
"If this was an event in isolation, one might say 'okay, we should view it on its own merits,' but when you view it in the backdrop of all of that, it becomes less clear," he said, also citing death threats against European defense executives and a bomb placed on a DHL aircraft in 2024.
European governments are contending with greater uncertainty over U.S. security guarantees after decades of underinvestment in defense, while facing a rise in unconventional but potentially devastating threats.
Hybrid warfare combines tactics such as cyberattacks, sabotage and disinformation to destabilize adversaries without triggering open military conflict.
Countries' abilities to withstand hybrid threats vary substantially across the continent, according to Kaushal. While Finland and Sweden have well-developed civilian defense programs reflecting their Cold War experience, much of Europe's infrastructure was built around economic efficiency rather than defense needs.
"As one goes further west in Europe, the level of preparation, both against hybrid attacks, but also just simple missile attacks of the kind that we've seen in Ukraine, is far less great," he said.
"Every attack generates a bit of resilience," he said, citing NATO's increased focus on threats to underwater cables and gas pipelines after the 2022 Nord Stream sabotage .
Oana Popescu-Zamfir, a senior research fellow specializing in European security at RUSI, said the recent incidents showed Europe had lagged in "preparing for something that we have known would be coming."
"We've been slow in adjusting to a new reality," she said. "We still tend to conceptually divide between peace and wartime, and that is no longer the case because we're not at war, but we're also not in peace time."
She said Europe was likely to face sustained hybrid attacks designed to achieve military objectives without conventional military force.
Popescu-Zamfir said Russia could draw on networks of proxies in Europe, some directly controlled and others more loosely coordinated, making responsibility difficult to trace directly to the Kremlin.
She told CNBC that "the damage that can be done is huge" in targeted attacks on internet-connected systems, citing the potential disruption of blood reserves.
The attacks are not a "piece of cake for Russia to carry out, but they're also not rocket science," she said, adding that they "can do tremendous damage in concrete terms and in terms of the psychological impact on our societies and the feeling that we are unprotected."
Blix said companies can take relatively straightforward steps to reduce their exposure.
"These are basic cyber hygiene things... You should not be allowed to connect industrial control systems and this kind of operational technology directly online without any proper security around it," he said.
Responsibility is split among product manufacturers, maintenance providers and grocery chains, making accountability unclear as each points to the others.
Blix said maintenance companies sometimes prioritize convenience by enabling remote access despite manufacturers' security guidance, while retailers may fail to enforce adequate cybersecurity standards among suppliers.
"What worries me is that we don't really do anything," Blix said, adding that "we are shuffling a lot of papers" and "doing a lot of risk assessments" but failing to take meaningful action.
Europe has also seen widespread unrest in recent months, adding political pressure as households grapple with high living costs.
Domestic political and economic tensions can also give foreign adversaries opportunities to deepen divisions, said Alexander Anderson, president and director of policy at the Centre for International Security and Economic Strategy.
He told CNBC that Russian and potentially Chinese influence operations may work to amplify those divisions.
"But we should be careful not to dismiss legitimate domestic grievances as the product of foreign interference," he said. "Doing so risks misunderstanding both the causes of political instability and the methods through which hostile actors seek to exploit it."
Weeks of nationwide protests, riots and strikes have increased pressure on the French government, complicating efforts to rein in public finances and deepening existing political divisions.
In Spain, demonstrations and a parliamentary impasse over the housing crisis led Prime Minister Pedro Sanchez to call a snap election. The vote is scheduled for Nov. 29. The far-right Vox party is expected to make gains, putting Sanchez's left-leaning government at risk of losing power.
Germany , Italy, Portugal and Albania have also seen unrest over rising living costs in recent weeks .
On Friday, protesters in Amsterdam tried to enter a Microsoft data center, Reuters reported.
Meanwhile, elevated energy prices, persistent inflation, sluggish growth and large budget deficits are pushing up borrowing costs and leaving governments with less room to support struggling households.
