 In the early 1990s, the U.S. Navy introduced a new concept based on the ARG, the "naval expeditionary task force" or, as it is also known, the "expeditionary strike group" (ESG).The ESG is similar to the ARG except that with the ESG concept, the U.S. Navy would be able to deploy almost double the number of independent operational groups, from 19 to 38.In addition, the ESG included surface warships and submarine escorts, similar to a carrier strike group (previously a carrier battle group).