In the United States Navy, the expeditionary strike group (ESG) is a coordinated group of surface ships, aircraft, submarines, and other naval assets. In contrast to carrier strike groups (CSGs), which emphasize air power and are led by a supercarrier, ESGs are strongly suited for amphibious warfare and are led by an amphibious assault ship. The ESG concept was introduced in the early 1990s, based on the Naval Expeditionary Task Force. The U.S. Navy fields nine expeditionary strike groups.

A carrier strike group (CSG) is a type of carrier battle group of the United States Navy. It is an operational formation composed of roughly 7,500 personnel, usually an aircraft carrier, at least one cruiser, a destroyer squadron of at least two destroyers or frigates, and a carrier air wing of 65 to 70 aircraft. A carrier strike group also, on occasion, includes submarines, attached logistics ships and a supply ship. The carrier strike group commander operationally reports to the commander of the numbered fleet, who is operationally responsible for the area of waters in which the carrier strike group is operating.