The U.S. on the Way to Strategic Invulnerability
... future [ 1 ]. Even though the SDI was officially closed, some projects were continued as part of the Ballistic Missile Defense Organization, which was renamed the Missile Defense Agency in 2002, and led to the creation of anti-missile systems such as Patriot PAC-3, Aegis BMD, THAAD and the Ground-Based Midcourse Defense system. Work continues on a number of projects that use active weapons based on new physical principles such as beam, electromagnetic, kinetic and super-high-frequency weapons, chemical ...