Largest Regional Cyber Exercise Enhances European and U.S. Cyber Defense Capabilities

Zagreb, Croatia – Over 100 cyber professionals from seven European nations and seven U.S. National Guard state partners convened for the Combined Adriatic Cyber Endeavor (CACE) 2026, the largest regional cyber defense exercise of its kind. Hosted by the Croatian Armed Forces at the Petar Zrinski Barracks from June 1 to June 11, 2026, the event aimed to bolster cooperation, coordination, and cyber defense expertise among participating countries. This marks the first time the Croatian Cyber Command has led such a significant multinational cyber exercise.

The exercise brought together participants from Albania, Bosnia and Herzegovina, Croatia, Kosovo, Montenegro, North Macedonia, and Slovenia. These European nations collaborated with their U.S. National Guard State Partnership Program counterparts from New Jersey, Maryland, Minnesota, Iowa, Maine, Vermont, and Colorado. The two-week initiative commenced with academic sessions and scenario development before progressing into the operational phase. Throughout the exercise, teams worked to simulate real-world cyber threats and defense strategies.

The CACE 2026 represented a significant evolution of ongoing regional efforts to strengthen cyber defense capabilities. A key development during the exercise was the first-time interconnection of cyber ranges operated by Croatia and Slovenia, facilitated by a U.S. security cooperation investment. These virtual training environments, donated to the Croatian and Slovenian armed forces in late 2023, expanded the training capacity and allowed participants to operate within a larger, more complex simulated cyber environment. The exercise simulated a fictional military mission where participating teams were tasked with defending a shared, unclassified network.

Participants were organized into defensive “blue teams,” responsible for threat hunting, incident response, reverse engineering, and network defense operations, along with documenting their findings and developing remediation plans. A “white cell” managed the exercise’s overall coordination, scenario progression, and participant guidance, ensuring training objectives were met. Offensive “red teams,” comprising some National Guard members and Croatian personnel, executed simulated adversary activities to challenge the blue teams. The overall infrastructure and cyber range environment were developed and maintained by a Croatian “green team” and SimSpace staff. This collaborative approach emphasized the importance of shared knowledge and joint problem-solving in addressing complex cyber threats.

The exercise underscored the growing cyber capabilities within the Adriatic region and established a foundation for future multinational training endeavors. Several participating nations are slated to receive similar virtual training environments, paving the way for continued regional cyber exercises. This initiative builds upon previous cooperation efforts, including the Adriatic Regional Security Cooperation Cyberspace Exercise held in 2024. Participants actively engaged in defending networks, exchanging technical knowledge, and fostering stronger relationships between allied and partner nations, ultimately enhancing regional stability and collective defense.

Article by Mel Anara, based upon information from the Defense Visual Information Distribution Service (DVIDS).

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