Sea-Based X-Band Radar is a floating, self-propelled, mobile radar station designed to operate in high winds and heavy seas. It is part of the United States Government's Ballistic Missile Defense System. The Sea-Based X-Band Radar is mounted on a 5th generation Norwegian-designed, Russian-built CS-50 semi-submersible twin-hulled oil-drilling platform. The hull was originally built at Vyborg Shipyard, hull number 101. Conversion of the platform was carried out at the AmFELS yard in Brownsville, Texas; the radar mount was built and mounted on the platform at the Kiewit yard in Ingleside, Texas, near Corpus Christi. It is based at Adak Island in Alaska but can roam over the Pacific Ocean to detect incoming ballistic missiles. The platform is classed by ABS and has the IMO number of 8765412.   Wikipedia