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Exercise Cyber Coalition, NATO's flagship Cyber Defence exercise, concludes in Estonia

NATO Supreme Headquarters Allied Powers Europe (SHAPE)

Dec 5 2025

TALLINN, Estonia -- NATO Allies and partner cyber defenders gathered in Tallinn, Estonia from Nov. 28 to Dec. 4, 2025, to test their ability to protect networks and critical infrastructure against realistic and complex cyber threats.

Exercise Cyber Coalition is NATO's flagship cyber defence exercise and one of the largest of its kind. This year, more than 1,300 cyber defenders from 29 NATO, 7 partner nations, Austria, Georgia, Ireland, Japan, South Korea, Switzerland, and Ukraine, the European Union, industry, and academia came together.

"Cyber Coalition is a combination of a year-long process where nations come together to collaborate, communicate, and share how they would execute, deter, and defend against an adversary. There is no boundary in cyber — it's worldwide. The better you can share and collaborate, the stronger and more resilient our collective defences become," said Commander Brian Caplan, the Exercise Director.

The scenarios were deliberately challenging and realistic, designed to prepare cyber defenders for real-world incidents. Participants faced simulated attacks, as well as disruptions to NATO and Allied operations.

The 2025 edition tested cyber defenders through seven complex scenarios, including attacks on critical national infrastructure, space-related cyber incidents, and "Ghost in the Backup''. Throughout the exercise, multiple threat actors conducted advanced and sophisticated cyber operations, targeting a NATO mission. These operations triggered coordination and collaboration among NATO and partner cyber defence teams, including through mechanisms such as the Virtual Cyber Incident Support Capability (VCISC).

Cyber defence is a key component of many NATO exercises, and cyber-specific exercises like Cyber Coalition help improve NATO's and Allies' abilities to defend their networks and coordinate effectively in the event of a cyber incident.

Cyber Coalition 2025 demonstrated the critical importance of teamwork and resilience in an increasingly interconnected and contested cyberspace. As cyber threats continue to grow in scale and sophistication, exercises like Cyber Coalition play a vital role in ensuring that NATO and its partners remain prepared to detect, deter, and defend against attacks in cyberspace.

Story by SHAPE Public Affairs Office