LGM-118 Peacekeeper Missile

The LGM-118 Peacekeeper, also known as the MX missile (for Missile-eXperimental), was a land-based ICBM deployed by the United States starting in 1986. The Peacekeeper was a MIRV missile that could carry up to 10 re-entry vehicles, each armed with a 300-kiloton W87 warhead in a Mk.21 reentry vehicle (RV). A total of 500 missiles were deployed starting in 1986, after a long and contentious development program that traced its roots into the 1960s.

LGM-118 Peacekeeper MissileMX was designed to allow the US to ride out a sneak attack by the Soviet ICBM fleet and then launch a counterattack. In order for the counterattack to be effective, MX had to have three qualities: the ability to be rapidly re-targeted, so that it would attack only those Soviet missiles known to be in their silos; enough accuracy to allow a small warhead to kill an enemy silo, so that more warheads could be packed on a single MX missile; and a basing system that meant enough of the missiles would survive an attack that the counterattack would be effective. Among these three, the basing issue remained an unsolved problem and the subject of much criticism during the MX's development.

After considerable debate, President Ronald Reagan announced that the newly named Peacekeeper would be put into service in existing LGM-30 Minuteman silos, a temporary solution until a final basing solution was decided. During the same period, the United States and the Soviet Union were involved in negotiations on the START II treaty, under which ICBMs were allowed to carry only a single warhead each. Because the Minuteman could carry a single warhead for far less money, and the Peacekeeper was proving highly unreliable in the field, the United States agreed to remove the Peacekeeper from their nuclear force in this treaty. Although START II was not ratified by the United States, the missiles were removed, with the last one going out of service on 19 September 2005. Their advanced W87 warheads were moved to Minuteman III.

LGM-118 Peacekeeper ICBM MIRVThe private launch firm Orbital Sciences Corporation has developed the Minotaur IV, a four-stage civilian expendable launch system using old Peacekeeper components.

The missiles were gradually retired, with 17 withdrawn during 2003, leaving 29 missiles on alert at the beginning of 2004, and only 10 by the beginning of 2005. The last Peacekeeper was removed from alert on 19 September 2005 during the final deactivation ceremony when the 400th Missile Squadron was inactivated as well. During the ceremony an Under-Secretary of the Air Force credited the Peacekeeper with helping to end the Cold War.

The Peacekeeper rockets are being converted to the satellite launcher role by Orbital Sciences, as the Minotaur IV (OSP-2), while their warheads will be deployed on the existing Minuteman III missiles. Parts of the missile 'Roll Control System' (RoCS) were reused during the Ares I-X test for the Ares V program. More details