In 1990, the Secretary of Defense designated SDIO as the central manager for developing and deploying a theater missile defense capability. As a part of this effort, the Army, with SDIO funding and guidance, is developing five ground-based theater missile defense systems: (1) the Theater High Altitude Area Defense (THAAD) system, (2) the Theater Missile Defense-Ground Based Radar (TMD-GBR), (3) the Extended Range Interceptor Technology (ERINT), (4) upgrades to the Patroit missile system (called 'Patriot PAC-3'), and (5) the Corps Surface-to-Air missile (called 'Corps SAM').