Chapter 4
Deterring Gray-Zone Warfare
Sam Mullins
“We have been handicapped…by a popular attachment to the concept of a basic difference between peace and war…and by a reluctance to recognize the realities of international relations—the perpetual rhythm of struggle, in and out of war.”
— George F. Kennan
U.S. Department of State Policy Planning Memorandum No. 269
May 4, 1948
Conceptualizing the Gray Zone
Throughout history, states have relied on a wide array of tools and techniques, ranging from disinformation and political interference to assassination and proxy warfare, to weaken adversaries and advance strategic objectives short of open war. These so-called gray-zone tactics, hostile acts that “fall between the traditional war and peace duality,” were visible during the Cold War but have risen to new prominence in the 21st century. Authoritarian and revisionist powers now exploit globalization and technology to expand influence, press territorial claims, and undermine the rules-based order, while avoiding more costly, direct confrontation with the United States.
China’s coercion in the South China Sea and Russia’s annexation of Crimea in 2014 are striking examples of this approach, visible tips of a steadily growing iceberg. In response, analysts have coined overlapping terms—irregular warfare, hybrid threats, and malign influence—all referring to hostile activities conducted below the threshold of conventional war yet outside accepted state behavior.
Gray-zone tactics vary in form—some overtly aggressive and illegal, others more insidious or technically lawful—but share common traits: they are coercive, corrupting, covert, and/or deceptive. Figure 4.1 illustrates this continuum, ranging from low-level, persistent non-kinetic activities to more aggressive, high-end coercion.
By design, these tactics exploit ambiguity in attribution and intent, generating uncertainty, slowing decision-making, and enabling aggressors to secure objectives before defenders can respond. When states hesitate—fearing escalation or political costs—deterrence falters. The result, as seen in both Chinese and Russian campaigns, is strategic gain without open conflict, incentivizing further use of gray-zone warfare.
