sentences:  The SC-21 Mission Need Statement was approved by the Joint Requirements Oversight Council between September–October 1994.The Defense Acquisition Board approved the project on 13 January 1995, allowing the program to proceed to Cost & Operational Effectiveness Analysis (COEA).The SC-21 COEA had an unusually wide remit, and studied a variety of designs from 2,500 tons to 40,000 tons.