Recent events in Crimea and the Donbass in eastern Ukraine have upended relations between Russia and the West, specifically the North Atlantic Treaty Organization (NATO) and the European Union (EU). Although Russia's actions in Ukraine were, for the most part, acts of outright aggression, Russia has been aiming to destabilize both its "near abroad" — the former Soviet states except for the Baltics — and wider Europe through the use of ambiguous "gray zone" tactics. These tactics include everything from propaganda and disinformation to election interference and the incitement of violence.

To better understand where there are vulnerabilities to Russian gray zone tactics in Europe and how to effectively counter them, the RAND Corporation ran a series of war games. These games comprised a Russian (Red) team, which was tasked with expanding its influence and undermining NATO unity, competing against a European (Green) team and a U.S. (Blue) team, which were aiming to defend their allies from Red's gray zone activities without provoking an outright war. In these games, the authors of this report observed patterns of behavior from the three teams that are broadly consistent with what has been observed in the real world. This report presents key insights from these games and from the research effort that informed them.