Sponsored by the Army Capabilities Integration Center and in collaboration with the Joint Staff's Deputy Directorate for Global Operations (Strategic Multi-Layer Assessment Branch), this report examines the emergence of gray zone competition and conflict as important pacers for U.S. defense strategy. The authors argue that gray zone challenges are unique defense-relevant issues sharing three common characteristics-hybridity, menace to defense and military convention, and profound and paralyzing risk-confusion. This report and its authors offer an important opening venture into a vexing strategic question for senior defense and military leadership on the subject of gray zone threats. Namely, how can the American defense enterprise adjust to an era of relentless revisionist and rejectionist opposition to U.S. power? On the one hand, purposeful U.S. competitors pursue meaningful revision of the U.S.-led status quo through campaign-quality combinations of influence, intimidation, coercion, and aggression.