Brussels (CNN) — In an unprecedented wave of cyber assaults, critical infrastructure across Europe was targeted early Monday in what officials are calling one of the largest coordinated cyberattacks in history. European Union cybersecurity agencies have pointed to Russian state-backed groups as the primary suspects behind the widespread disruptions.

Power grids, financial institutions, airports, and healthcare systems across more than 15 countries were affected. Several major European banks reported temporary outages, and airports in Frankfurt, Paris, and Madrid experienced system failures that caused extensive flight delays. Emergency services in parts of Germany and Poland were forced to revert to analog communications after losing digital capabilities.

"This is a direct attack on European sovereignty," said European Commission President Ursula von der Leyen at a press briefing. "We will respond with unity, strength, and resilience."

The Kremlin has officially denied involvement, dismissing the accusations as "baseless and provocative."

At the same time, NATO forces reported unusual naval movements in the North Atlantic. According to U.S. European Command (EUCOM), at least six Russian naval vessels, including two destroyers and a submarine, were detected maneuvering near critical undersea cable routes between Europe and North America. Additional allied naval assets have been deployed in response to what a senior Pentagon official described as "a significant and deliberate show of force."

"This pattern of behavior is deeply concerning," said Admiral James Thornton, commander of NATO's Allied Maritime Command. "We are closely monitoring all maritime traffic and are prepared to safeguard transatlantic security."