JDAM is not intended to replace any existing weapon system; rather, it is to provide accurate delivery of general purpose bombs in adverse weather conditions. The JDAM will upgrade the existing inventory of Mk-83 1,000- and Mk-84 2,000-pound general purpose unitary bombs and the 2,000-pound hard target penetrator bomb by integrating a guidance kit consisting of an inertial navigation system/global positioning system guidance kit. The 1,000-pound variant of JDAM is designated the GBU-31, and the 2,000-pound version of the JDAM is designated the GBU-32. JDAM variants for the Mk-80 250-pound and Mk-81 500-pound bombs are designated GBU-29 and GBU-30, respectively.

The JDAM will be continuously updated by aircraft avionics systems prior to release. Once released, the bomb's INS/GPS will take over and guide the bomb to its target regardless of weather. Guidance is accomplished via the tight coupling of an accurate GPS with a 3-axis INS. The Guidance Control Unit provides accurate guidance in both GPS-aided INS modes of operation and INS-only modes of operation. This inherent JDAM capability will counter the threat from near-term technological advances in GPS jamming. The weapon system allows launch from very low to very high altitude and can be launched in a dive, toss, loft or in straight and level flight with an on-axis or off-axis delivery. JDAM also allows multiple target engagements on a single pass delivery. JDAM provides the user with a variety of targeting schemes, such as preplanned and inflight captive carriage retargeting.
JDAM is being developed by Lockheed Martin and Boeing [McDonald Douglas] and will be operational by 1998. In October 1995, the Air Force awarded a contract for EMD and for the first 4,635 JDAM kits at an average unit cost of $18,000, less than half the original $40,000 estimate. As a result of JDAM's pilot program status, low-rate initial production was accelerated nine months, to the latter half of FY 1997. JDAM will be carried on virtually all Air Force fighters and bombers, including the B-1, B-2, B-52, F-15E, F-16, F-22, F-117, AND F/A-18. JDAM was certified as operational capable on the B-2 in July 1997.

The JDAM program is nearing the end of its development phase. More than 250 flight tests involved five Air Force and Navy aircraft. The 11 Feb 1998 drop from a B-1B was the 122nd guided JDAM launch. Early operational capability JDAMs have been delivered to Whiteman Air Force Base, Mo., and low-rate, initial production JDAM deliveries begin on 02 May 1998.

The JDAM product improvement program may add a terminal seeker for precision guidance and other system improvements to existing JDAMs to provide the Air Force with 3-meter precision and improved anti-jamming capability. The Air Force is evaluating several alternatives and estimates that the seeker could be available for operations by 2004. The seeker kit could be used by both the 2,000-pound blast fragmentation and penetrator JDAMs.