A Launch service provider (LSP) is a type of company which specialises in launching spacecraft. It is responsible for the ordering, conversion, or construction of the carrier rocket, assembly and stacking, payload integration, and ultimately conducting the launch itself. Some of these tasks may be delegated or sub-contracted to other companies. For example, the United Launch Alliance subcontracts the production of GEM solid rocket motors for its Atlas V, Delta II and Delta IV rockets to Alliant Techsystems. An LSP does not necessarily build all the rockets it launches.