In an era of rising global competition, U.S. challengers and rivals are increasingly looking to achieve competitive advantage through gray zone activities-that is, acts of aggression that remain below the threshold of outright warfare. In this report, RAND researchers identify eight common characteristics of such aggression (e.g., unfolds gradually, is not attributable) and develop a framework for assessing the health of U.S. and partner deterrence in the gray zone.

They apply the framework to three cases: Chinas aggression against the Senkaku Islands, Russias aggression against the Baltic states, and North Koreas aggression against South Korea. The authors conclude that U.S. and partner deterrence of gray zone activities is in a reasonably strong, though mixed, condition in each of these three contexts. Finally, the authors outline the implications of their findings for the U.S. Army. Among these implications are that maintaining a local presence and posture plays an important role in conveying likely responses to aggression, and clear statements of shared intent to respond to specific actions are critical.