War vintage structures remained, new dormitories were built, and a new headquarters complex completed in 1974 for the 314th AD and 51st CW(T) replaced 71 Quonset huts that were destroyed by fire three years earlier. In 1979 and 1980, construction of on-base family housing and additional community-support facilities gave the base a sign of stability. Establishment of the Combined Forces Command in 1978 further set the future of Osan AB. The evolving role of USAF's CFC mission in South Korea led to activation of Headquarters Seventh Air Force on September 8, 1986. It replaced the 314th AD as the U.S. Air Force component command. Construction on Osan AB during the 1980s was dictated largely by mission changes and enhancements, and the threat from North Korea. Introduction of the F-16 Fighting Falcon in 1988 led to construction of hardened aircraft shelters, a new on-base munitions storage area, and upgrades to unaccompanied personnel housing. The presence of U-2 reconnaissance aircraft was classified until 1978, though the planes could be seen at takeoff and landing. Post-Cold War While the face of Osan AB slowly changed in replacing its 40-year-old Korean War-vintage structures, the base experienced a lengthy period with little or no military construction program projects. However, other funding sources allowed base officials to add community-type facilities. Arrival of the 25th Fighter Squadron and its A/OA-10s in October 1993 and two MIM-104 Patriot batteries in May 1994 also necessitated some new construction. Other than these events, base officials primarily concentrated on improvements in facility protection due to the threat from North Korea's reliance on medium-range SCUD missiles. Annual runway repairs furthermore only attested to the aging of Osan AB as the base witnessed only modest changes in its structural appearance during the 1990s. It was not until 1998 that HQ PACAF renewed emphasis on improving the base's support structure. Increasing infrastructure failures seriously detracted the 51st Fighter Wing from conducting its deterrence mission. HQ PACAF subsequently provided the base with funds under the "Fix Korea Initiative." More than $200 million was invested in upgrading or replacing the water, sewage and electrical distribution systems over the following six years. Additionally, mid- and long-range plans for the base foresaw a dramatic facelift of Osan AB that included new on-base family housing, new community-support facilities, and replacement of many industrial structures that supported the 51st FW mission. As South Korea's military grew and matured into a