The origins of SC-21 lie in the realization by Admiral Joseph Metcalf III that new technologies such as vertical launch missiles permitted a complete rethink of warship design. He established a steering group, Group Mike, to study the possibilities. Group Mike sponsored two studies in 1987: the Ship Operational Characteristics Study (SOCS) and the Surface Combatant Force Requirement Study (SCFRS). Respectively, these studies sought to identify the operational characteristics required of an escort ship and estimate how many such ships were required by the fleet. Since it was expected at that time that the Navy would be fighting prolonged campaigns in the Norwegian Sea, SOCS put an emphasis on ships' continuing ability to fight after an initial Soviet attack. This in turn called for larger, more survivable escort ships than had historically been the norm, around 12,000 tons, and for networking sensors and weapons together so that they could be used by the task force as a whole even if an individual ship had their radar disabled. Survivability also called for the bridge and Combat Information Center to be combined and "buried" in the heart of the ship, and for the ship to use electric drive to distribute the engineering around the ship. This would provide more room for weapons as well as the scope for future weapons such as railguns and lasers. SCFRS suggested that the Navy should not replace the Perry class frigate for convoy escort duties, but concentrate on building front-line combatants that could be assigned to less demanding convoy duties in their later years.
DD 21 was to be a multimission destroyer tailored for land attack warfare. DD 21 was required to support ground forces as a primary mission, in addition to performing traditional destroyer missions (i.e., anti-air, anti-surface, and undersea warfare). In that regard, DD 21 represented a departure from past design efforts, which were focused primarily on the deep-water threats of the Cold War era. The DD 21 was to be a true fleet destroyer, capable of handling any mission that a Fleet commander might ask, from key wartime missions in land attack and undersea warfare to the equally important presence missions, noncombatant evacuations, escort, and diplomatic missions that have been closely associated with Navy destroyers for almost a century.