What Joint Direct Attack Munitions Could Do For Ukraine
JDAMs could provide Ukraine with an urgently needed all-weather precision air-to-ground capability with some standoff range.
Ukraine may be in line to receive Joint Direct Attack Munition, or JDAM, precision air-to-ground weapons, as one of the latest additions to the supply of arms flowing from the United States and its allies. The JDAM would provide the Ukrainian Air Force with an entirely new capability to attack precise coordinates on the ground while offering a degree of standoff protection to the launch aircraft, although any such transfer remains unconfirmed for now.
According to an article in The Washington Post, which is based on disclosures from unnamed U.S. officials, the Biden administration plans to supply JDAM kits that “convert unguided aerial munitions into ‘smart bombs.’” Each JDAM kit consists of the guidance package and control section, tailfins for steering, and strakes attached to the bomb for stability and a limited gliding capability. This kit is then mated to an existing bomb body, normally a variant or derivative of the ubiquitous Mk 80 series of weapons.
Broadly speaking, the JDAM kit can be mated with 2,000-pound Mk 84, 1,000-pound Mk 83, and 500-pound Mk 82 ‘dumb’ bombs, as well as the penetrating versions of these same weapons.
Interestingly, The Washington Post report also brings up the possibility of some kind of ground-launched weapon, although there is no known ground-launched JDAM derivative. Ukraine has, however, recently been connected with the possible transfer of the Ground-Launched Small Diameter Bomb, or GLSDB, a precision strike weapon based on the air-dropped Small Diameter Bomb.
In its basic form, the JDAM guidance package uses an inertial navigation system (INS) and a GPS receiver, which together ensure that the bomb can hit its chosen target with a high degree of accuracy (within tens of feet) in any weather. It is ‘fire and forget,’ in that the launch aircraft can turn away and run after release. Should the GPS signal be jammed or otherwise unavailable, the accuracy is reduced, but it is still within the weapon’s effective blast area in most cases.
Although unpowered, the JDAM provides a degree of standoff range, being able to hit targets at up to about 15 miles away with launch from a typical fast-jet's speed and altitude.
For Ukraine, the JDAM would offer the advantages of a high degree of precision to attack Russian ground forces and other objectives, as well as a relatively low cost. In the 2021 Fiscal Year, the U.S. Air Force paid an average of $21,000 for each JDAM kit (including the multi-mode Laser JDAM kits). Meanwhile, a standard, unguided Mk 82 500-pound bomb cost $4,000, increasing to $16,000 for a 2,000-pound Mk 84 unguided bomb.
This compares to the average of $70,000 the U.S. Air Force paid for a single AGM-114 Hellfire missile in the same period, or over $1.2 million for a single AGM-158 Joint Air-to-Surface Standoff Missile (JASSM) round.
The Laser JDAM remains a possibility for Ukraine, too. Although integration would be more challenging, the Laser JDAM’s dual-mode GPS and laser guidance would, in theory, allow attacks on moving targets. The basic JDAM is limited to striking targets with fixed coordinates, although it can do this in all weather, while the laser version is restricted to clear-weather use. However, the laser version would require a targeting pod integrated with the aircraft, or a designator on the ground, to make full use of its capabilities, although it can also be used in standard GPS/INS mode.
It’s still unclear at this point whether President Biden has actually approved a transfer of JDAMs to Ukraine, although the fact that officials are now speaking of such a development at all is significant.
The Washington Post article only mentions JDAM kits, rather than the associated bombs they would be mated to. Logically, they would simply be combined with Mk 80 series bombs, a fairly straightforward process, and there seems no reason why the U.S. government would not supply them. A much less likely possibility would involve combining the JDAM kits with some of the Soviet-era freefall bombs currently in the Ukrainian inventory, although there is no guarantee this would even be feasible.
The issue of integrating the complete JDAM rounds with the Ukrainian Air Force’s existing combat aircraft would pose the biggest challenge. Potentially, the MiG-29 or Su-27 fighter jets, the Su-24 strike aircraft, or even Su-25 ground-attack aircraft could carry JDAMs, although each would require a degree of adaptation to ensure that the interface between the jet, the weapon, and the pilot in the cockpit worked as required. It seems likely that Ukraine would employ the JDAM in a pre-programmed mode, with target coordinates inputted on the ground before flight. This would remove the flexibility to retarget in flight, but would still offer valuable precision with some standoff range against known targets.
There is, of course, a precedent for the Ukrainian Air Force taking existing Western-sourced precision-guided munitions and adapting them for use by its Soviet-era fighters. The Ukrainians appear to have relatively quickly made modifications to both MiG-29 and Su-27 jets that allow them to use AGM-88 High-speed Anti-Radiation Missile, or HARM, weapons. The U.S. government also has experience in integrating the JDAM with somewhat unusual aircraft types, to meet urgent operational requirements, notably including OV-10 Bronco turboprop attack aircraft operated by the Philippines.
A video that includes sequences of Ukrainian MiG-29s firing AGM-88 High-Speed Anti-Radiation Missiles:
Since the summer, Ukrainian jets have been using HARMs to attack Russian air defense systems, the missiles homing in on enemy radio-frequency emissions. Exactly how the HARM was integrated is unclear, but it seems highly likely that it limits some of the more advanced operating modes that would be available when launched from a Western fighter jet that is fully integrated with the weapon. This is an aspect of the anti-radiation missile that we have discussed at length in the past. On the other hand, whatever route was taken, the Ukrainian Air Force appears to be very happy with the results.
There is also the issue of training pilots and ground crew to operate the JDAM, but the experience with HARM suggests this is far from insurmountable. Since JDAMs are widely used by Ukraine’s allies in Europe, then potentially some training could be carried out in one of these countries.
Interestingly, part of the work to make Ukrainian jets compatible with HARM involved fitting the selected aircraft with the LAU-118 pylon that carries the missile. This same pylon should also be suitable for carrying Mk 80 series bombs, or their JDAM equivalents.
Since its introduction, the JDAM has often been employed in permissive or less-contested environments, allowing the launch aircraft to fly at higher altitudes, from where the JDAM has a longer glide range. There is also the option of adding wing kits to the JDAM, for a further range increase, although this is by no means a common modification and there’s no indication that it might be under consideration for Ukraine. These are also not stockpiled items.
The highly dangerous air defense environment over the Ukrainian front lines — due to a combination of Russian fighter jets with long-range missiles and a wide variety of ground-based air defense systems — forces Ukrainian jets to fly much lower, for their own safety, in many cases when near the front lines. Dropping JDAMs from a lower level reduces their standoff range, but would still provide a degree of accuracy unavailable to attacks made using unguided bombs or — as seen in the video below — rockets. Still, release at the very low altitudes that Ukrainian aircraft often fly at is not possible for JDAM employment using basic drop profiles. One possible attack profile might involve a jet approaching the objective at low level, before popping up and releasing the JDAM in a lofted trajectory to hit a target close to the front lines.
The JDAM also seems to fit with Washington’s generally cautious approach to providing Ukraine with advanced weaponry, especially more provocative long-range weapons of the kind that would be able to strike targets deeper within Russia. It’s for this reason that Ukraine has been supplied with M142 High Mobility Artillery Rocket Systems, or HIMARS, but these weapons have apparently been modified to prevent them from firing any variant of the Army Tactical Missile System (ATACMS) short-range ballistic missile. Kyiv has long wanted access to ATACMS, but this weapon has a range of nearly 200 miles and would greatly extend the number of Russian targets that could be held at risk.
Nevertheless, JDAMs would fill an important gap for Ukraine, providing a heavier precision-strike capability with a weapon up to the 2,000-pound class. Even the 500-pound version would provide a greater punch than M31 rockets fired by HIMARS, in some regards. The kind of standoff aerial attack possible with JDAM would be especially useful for hitting Russian key targets near the front lines, even ones that are large and heavily fortified. The other big advantage the JDAM offers is the sheer number of these weapons available from the United States and many of its allies; in that sense, it shares many of the benefits of supply with the AIM-120 AMRAAM.
More generally, the fact that JDAM now appears to be under consideration for Ukraine seems indicative of how the scope of aid supplied and facilitated by the United States seems to be expanding. Similarly, there is now reported movement on the supply of Patriot long-range air defense systems, while the proposal for GLSDB (for which Ukraine would be the first operator) would have been unconscionable just six months ago.
With a new round of U.S. arms transfers expected to be announced soon, it would not be altogether surprising if the JDAM is included on the list. Exactly how the Ukrainian Armed Forces would employ it remains unclear, but their track record with HARM suggests that successful integration and combat usage should be well within their reach.
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