The Department of Defense's (DOD's) programs to
develop new satellites to alert U.S. military commanders to foreign missile launches, and to support
missile defense objectives, are controversial because of cost growth and schedule slippage.
SBIRS-High, managed by the Air Force, would replace existing Defense Support Program "early
warning" satellites. The Space Tracking and Surveillance System (STSS, formerly SBIRS-Low),
managed by the Missile Defense Agency, would perform missile tracking and target discrimination
for missile defense objectives. The SBIRS-High program has breached Nunn-McCurdy cost growth
limits several times, resulting in several program restructurings. This is the final edition of this
report.