This article examines the U.S. military’s plans for carrying out combined joint operations across multiple theaters and domains in the twenty-first century. It summarizes the most likely strategic and operational approaches available to future adversaries, such as anti-access/area denial (A2/AD), gray zone warfare, and other asymmetric methods. The article also considers the respective challenges posed by the two likely catalysts for military operations: contested norms and persistent disorder. The U.S. military response to this strategic context is still forming, but there are common themes among the services: the recognition that future operations will entail greater risk; the need to disperse forces to survive on a more lethal battlefield; a desire to create networked forces attacking with a combination of physical and nonphysical (cyber and electronic warfare); and a rebalancing of force structure in terms of both weapon sophistication and mission type.