Four GBU-39 small diameter bombs. Image – U.S. Air National Guard/Staff Sgt. Jordan Martin
On January 30, 2024, press reports indicated deliveries of the Ground-Launched Small Diameter Bomb (GLSDB) to Ukraine may commence this week. Thus far, the U.S. Department of Defense has not confirmed or denied these reports.
On February 3, 2023, the United States government announced an aid package for Ukraine that would include the GLSDB. There have been several announced delays in delivering the GLSDB to Ukraine over the past year.
The Ground-Launched Small Diameter Bomb is a variant of the standard GBU-39/B SDB, mated with the 227mm M26 rocket. Boeing and Saab partnered to develop an inter-stage adapter to connect he GBU-39/B SDB and the M26. This enables the GLSDB to be fired from an unmodified M270 Multiple Launch Rocket Systems (MLRS) or M142 High Mobility Artillery Rocket System (HIMARS). The M270 MLRS mounts two “six pack” launch pods, carrying twelve 227mm rockets; while the M142 HIMARS mounts a single six-pack, carrying six 227mm rockets. The GLSDB also comes with its own container/launcher, providing an alternate launch capability without the need for an M270 MLRS or M142 HIMARS. To date, Ukraine has reportedly received at least 20 HIMARS systems from the United States.
GBU-39 deployed. Image – USAF
The GLSDB carries 35-lb (16-kg) multipurpose penetrating and blast-and-fragmentation warhead; and has a range of 93 miles (150 km). It reportedly has an accuracy of within 1 meter; and has been tested successfully against targets moving at 50 miles per hour (80 km/hr).
The GLSDB has not yet been deployed by the U.S. Army. Thus, any use in Ukraine will represent the weapon system’s operational debut.
Given the paucity of open-source information about GLSDB transfers to Ukraine, the Forecast International Weapons Group cannot properly assess the impact of these transfers upon the Small Diameter Bomb program at this time. We expect the impact on the existing SDB production schedule to be minimal.
The GLSDB is not a game-changer by any means. Rather, it offers Ukrainian forces an expanded rocket artillery capability against Russian targets behind the immediate front lines.
