CSG meaning in Military and Defence ?

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.

Strike groups comprise a principal element of U.S. power projection capability; a single supercarrier holds enough firepower to rival the air forces of entire nations. Previously referred to as carrier battle groups (a term still used by other nations), they are often referred to by the carrier they are associated with (e.g., Enterprise Strike Group). As of March 2016 there are 10 carrier strike groups in the U.S. Navy.

The carrier strike group is a flexible naval force that can operate in confined waters or in the open ocean, during day and night, in all weather conditions. The principal role of the carrier and its air wing within the carrier strike group is to provide the primary offensive firepower, while the other ships provide defense and support. These roles are not exclusive, however. Other ships in the strike group sometimes undertake offensive operations (launching cruise missiles, for instance) and the carrier's air wing contributes to the strike group's defense (through combat air patrols and airborne anti-submarine efforts). Thus, from a command and control perspective, carrier strike groups are combat organized by mission rather than by platform.