U.S. Ballistic Missile Defense (Jonathan Masters, Council on Foreign Relations)
www.cfr.org/defensehomeland-security/us-ballistic-missile-defense/p30607
U.S. missile defense systems are designed to protect the U.S. homeland, deployed military forces, and allies from limited ballistic missiles attacks. The Pentagon originally sought development of ballistic missile defense (BMD) technology to counter the Soviet nuclear threat during the Cold War, but focus in the twenty-first century has shifted to defending and deterring potential strikes from regional actors, particularly Iran and North Korea. In March 2013, the Pentagon announced it would shore up missile defenses on the U.S. west coast to guard against a growing North Korean threat, while effectively cancelling the final phase of plans to deploy missile interceptors in Europe over the next decade. Proponents of BMD stress its role in the projection of U.S. power abroad and its value as a deterrent, while critics highlight BMD's largely unproven technology and high costs.