Tallinn, Estonia – The flagship cyber defense exercise Cyber Coalition 2025 of NATO ended on December 4, 2025, in Tallinn, Estonia, after seven hard days of simulating highly complex, real-world digital threats. Over 1300 cyber defenders representing 29 NATO members and seven partner countries, including Ukraine, Japan, and South Korea, were involved in the massive war game.
The drill, only 130 miles off the Russian border, was aimed at determining the capability of the alliance to protect military and civilian digital infrastructure against a rolling, sophisticated enemy attack.
Although no particular country was named by the officials, it was clear that Russia and China were the main sources of threats in the minds of the participants.
Simulated Chaos and Complex Scenarios
The Cyber Coalition 2025 presented the participants with seven complicated situations, including attacks on critical national infrastructure or cyber-related incidents in the sphere of space. It was a game pitted against a fictional NATO ally, “Andvaria,” and its antagonistic neighbor, “Harbadus,” fighting over a fictitious island in the North Atlantic named “Icebergen”.
The simulated attacks started to increase rapidly and plunged troops into situations involving Sudden Power Blackouts, attacks on fuel management systems, and power grids, forcing rapid efforts to ration supplies and disconnect networks; Space Communication Loss, an attack on one of the satellite internet providers, such as Starlink, in which communications between Earth and space were disrupted in a series of stages. This extended into intelligence, surveillance, GPS, banking, and even military coordination.
The scenarios also included Ghost in the Backup, a scenario that examined the power of restoring systems following an advanced malware breach, and Information Warfare, where participants struggled with the dissemination of fake news on social media, such as false headlines about crowds of people and leaking classified information, having to address a crisis on both physical and online levels.
The Exercise Director, Commander Brian Caplan, a US naval officer, emphasized the significance of the drill, “There is no boundary in cyberspace. Adversaries can go into one nation and pivot into another nation. Something that affects one nation can have a second- or third-order effect in other nations. So it’s really important that these nations are communicating, building that trust, that relationship.”
The Importance of Collaboration
One of the most important lessons that was learned through exercise was the importance of global cooperation. As attacks snowballed, no single country had the full picture of the threat. Cyber defenders, military and civilian personnel operating from Tokyo to Texas, had to rapidly share fixes and warnings.
To cope with this complexity, NATO also announced it is testing an AI-based chatbot that can assist commanders to have a quick situational understanding and propose steps to respond to the situation during an event in case of a fast-moving cyber-attack.
Context of Real-World Threats
The practice is timed on an escalating real-life tension. Recently, NATO Secretary General Mark Rutte accused the Russians of becoming more and more reckless.
Microsoft analysis mentioned during the exercise showed that the frequency of Russian cyber-attacks on NATO states had risen by 25% throughout the year before June 2025.
The alliance has also blamed Russia, through its GRU military intelligence, for attacks and charged China with malign hybrid and cyber-attacks.
Military lawyers were present during the exercise to consult on the legality of the response to the attacks that were usually initiated by shadow proxies and targeted civilian assets.
While the seven-day war game was demanding, officials offered cautious reassurance; the alliance is “surviving at the end of the day,” demonstrating that NATO and its partners remain vital in defending an increasingly interconnected and contested cyberspace.
