Minuteman Launch Facility S-03 (Sierra-03 LF), Yoder Wyoming

S-03 was one of those Cold War places that worked because it almost disappeared into the landscape: a fenced launch site east of Yoder, Wyoming, surrounded by open agricultural country, with its real importance buried below the surface. During its active years, the site did not need a tower, runway, or large aboveground complex to matter. Its purpose was to keep a solid-fueled ICBM sealed inside a hardened silo, connected by buried cable to Sierra Flight's launch-control crew, and ready as part of a deterrent system whose power was measured by what never had to be launched.

Launch Facility S-03 was an unmanned missile launch facility assigned to Sierra Flight in the F.E. Warren Air Force Base missile field. Its parent control site was the S-01 Missile Alert Facility / Launch Control Center. The site code is S-03.

S-03 belonged to the 400th Strategic Missile Squadron during the Strategic Air Command era and later to the 400th Missile Squadron lineage in the 90th Missile Wing. It began as part of F.E. Warren's LGM-30B Minuteman I force, was later part of the base's LGM-30G Minuteman III field, and then was converted for the LGM-118A Peacekeeper missile. It is no longer an active missile site. The Peacekeeper strategic-alert mission ended on 2005-09-19, when the Air Force announced that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.

S-03 was one of ten launch facilities assigned to S-01 and Sierra Flight. The Sierra Flight facilities were dispersed across the agricultural and ranching landscape around Yoder, Torrington, Hawk Springs, Lyman, and surrounding parts of Goshen and Platte counties. That geography was not incidental. Minuteman and Peacekeeper launch facilities were separated from each other and from their launch-control center so that a single attack could not destroy an entire flight at once.

The immediate setting of S-03 is rural southeastern Wyoming. The 2013 Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination treated Yoder as one of the closest towns to former 400th Missile Squadron launch facilities, listing it about four miles from S-3 and S-11. The same assessment described the former 400th Missile Squadron Peacekeeper deployment area as north and east of F.E. Warren AFB, spread across parts of Goshen, Platte, and Laramie counties.

A typical launch facility in this former Peacekeeper group consisted of a launcher and launch facility support building inside a security fence. The 2013 environmental assessment states that Peacekeeper launch-facility sites averaged approximately 1.6 acres, with an interior about 90 feet deep, a 28-foot headworks section, and a 12-foot-diameter launch tube below the headworks.

Public F.E. Warren history states that the base's Minuteman III weapon system replaced Minuteman I in 1975 and that Minuteman II was not deployed at F.E. Warren. The 400th Strategic Missile Squadron had already marked this transition in November 1973 by becoming the first all-Minuteman III squadron at Warren.

In the 1980s, the Air Force chose to deploy the LGM-118A Peacekeeper in modified Minuteman III silos at F.E. Warren. The Peacekeeper, originally known as MX, was a much larger and more advanced ICBM than Minuteman. Official F.E. Warren sources describe it as a four-stage missile using a cold-launch system: high-pressure steam ejected the missile from the silo before the first-stage motor ignited after the missile cleared the silo. By 1988, F.E. Warren had 50 Peacekeeper missiles on alert in modified Minuteman III silos, all within the former 400th Missile Squadron field.

For S-03, alert status did not mean the missile was visible aboveground or continuously exposed. The missile remained sealed inside the hardened launch facility. Alert meant that the launch facility, missile, communications, security systems, power and environmental systems, maintenance program, and crewed launch-control network were maintained in an operational readiness posture under national command authority. The human launch-control role for S-03 belonged to the crewed S-01 Launch Control Center, not to the unmanned launch facility itself.

The Peacekeeper system was retired after the Cold War as U.S. strategic-force requirements changed and arms-control limits reduced the role of multiple-warhead ICBMs. Air Force public reporting stated that Peacekeeper deactivation began in October 2002 and that the final phase came in September 2005. On 2005-09-19, the Peacekeeper mission ended at F.E. Warren, and a missile combat crew officer at Papa-01 confirmed that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.

The 2013 Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination gives the best public description of what happened to former Peacekeeper launch facilities such as S-03 after missile retirement. The assessment states that Peacekeeper missiles within the former 400th Missile Squadron had been removed, that previous deactivation activities included removal of missiles and salvageable items, that fluids had been drained from fueling, coolant, and hydraulic systems, and that electrical filters, switches, and power-supply batteries had been removed. After deactivation, gates were secured and each launch facility was placed in caretaker status.

New START then shaped the physical end of the site as a missile launch facility. The 2013 assessment evaluated dismantlement of 50 Peacekeeper launch facilities and five MAFs assigned to F.E. Warren AFB. Launch-facility dismantlement could include explosive implosion or backfill. Under the described process, the silo door would be removed, dismantled, or destroyed; the headworks would be dismantled or destroyed; the silo and launch facility support building would be filled with debris, gravel, or earth; and the site would be graded. New START verification required the launch facility to remain visible during dismantlement and open for a 60-day observation period after the headworks were dismantled before final filling and grading.

For the full Sierra Flight narrative, see S-01 Missile Alert Facility / Launch Control Center

Cronology

• 1963-07-01 - The 90th Strategic Missile Wing was activated at F.E. Warren AFB.
• 1964-07-01 - The 400th Strategic Missile Squadron was organized during F.E. Warren's Minuteman expansion.
• 1965-06 - F.E. Warren's Minuteman field reached full operational status at the wing level; S-03 is treated as part of that mid-1960s operational Minuteman field.
• 1973-11 - The 400th Strategic Missile Squadron became the first all-Minuteman III squadron at F.E. Warren.
• 1975 - F.E. Warren's public wing history places replacement of Minuteman I by Minuteman III in 1975; S-03 is treated as part of that modernized Minuteman III field before Peacekeeper conversion.
• 1982-11-22 - President Ronald Reagan announced plans to deploy the MX / Peacekeeper missile at F.E. Warren.
• 1984-07 - Construction began for Peacekeeper support facilities at F.E. Warren.
• 1986-01-23 - The 400th Strategic Missile Squadron began phasing out Minuteman III missiles in preparation for Peacekeeper deployment.
• 1986 - Peacekeeper became operational at F.E. Warren, with the first 10 missiles deployed there according to F.E. Warren's public Peacekeeper fact sheet.
• 1988 - F.E. Warren's public wing history states that 50 Peacekeeper missiles were brought on alert in modified Minuteman III silos.
• 2005-09-19 - The Peacekeeper alert mission ended at F.E. Warren; Air Force public releases stated that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.
• 2007-06 - The 2013 silo-elimination environmental assessment bibliography lists a Toltest, Inc. Tank Closure Report for Launch Facility Sierra-3, F.E. Warren AFB, Wyoming.
• 2011-02-05 - New START entered into force, setting treaty deadlines that shaped elimination of deactivated silos and associated alert facilities.
• 2013-03 - The Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination evaluated dismantlement of 50 Peacekeeper launch facilities and five MAFs assigned to F.E. Warren AFB.
• 2013-08 - Air Force Global Strike Command reported that elimination of F.E. Warren's former Peacekeeper launch facilities had begun.
• 2018-02-04 - New START's elimination deadline applied to selected deactivated silos and associated alert facilities.

Read about the Peacekeeper Missile at F.E. Warren AFB

All Peacekeeper Missile Silo Locations

All Minuteman/Peacekeeper Missile Silo Locations