A carrier strike group (CSG) is a type of carrier battle group that is a principal element of U.S. power projection capability. 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, and a carrier air wing of 65 to 70 aircraft. The CSG 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 CSG is to provide the primary offensive firepower, while the other ships provide defense and support. These roles are not exclusive, however, and other ships in the strike group sometimes undertake offensive operations, such as launching cruise missiles, while the carriers air wing contributes to the strike groups defense through combat air patrols and airborne anti-submarine efforts. Carrier strike groups can strike targets from 1,000 miles away and can defend against air, missile, and submarine attack, and can maintain maritime security over an area of hundreds of square miles. As of March 2023, there are 11 carrier strike groups in the U.S. Navy, 10 of which are based in the United States, and one is based in Japan.