Special thanks to BarbeCul who has been volunteering invaluable editing on my diaries
Ukraine currently has a weapon in its arsenal that arguably has the biggest capacity to deal a logistical deathblow to Russia, and it only costs $25,000 per unit. That’s about 1/5 the cost of a HIMARS GMLRS missile. It’s called the JDAM-ER, or the Joint Direct Attack Munition Extended Range.
Although the aircraft delivered weapon has a potential for destruction that goes far beyond that of the HIMARS, figuring out how to safely get this weapon through Russian Air Defenses to hit valuable targets will likely require creative coordination between offensive deployment of HARM Missiles, Patriot Missile Systems to overcome Russian signal jamming, ground and air based anti-aircraft defenses.
What is JDAM-ER?
First delivered to Ukraine in an aid package in December 2022, it did not get used in the field until early March because it took some work by US and Ukrainian engineers to affix US made Mark Series bombs (that JDAMs attach to) to Soviet aircraft weapon fixture points . An additional challenge was getting it compatible with the Mig 29 / Su-24 fighters that are the workhorses of the Ukrainian air force. There was both the issue of physically attaching the bombs, as well as getting the guidance systems to communicate with the fighters’ Soviet computing systems.
The work was completed sometime in March, and Ukraine confirmed its first combat deployment of the JDAM-ER on March 31, 2023. So this is a weapon that is just making its first appearance in the Russo-Ukrainian War.
Details of the JDAM-ER delivered to Ukraine, including information about what types or how many, has been kept secret. However, it’s known that Ukraine has now received 2 shipments of JDAM-ERs in December 2022, and they were again included in the US aid package in early April preceding the Ramstein 11th conference (where Ukraine aid is internationally coordinated). It was noted that among the types Ukraine received included those for the most powerful type of JDAM-ER for 2000lb bombs.
To be precise, it’s not actually a bomb itself, but an electronic kit that is applied to a regular “dumb” bomb with a pair of fins, that turns an ordinary bomb into a long range glide bomb.
In a perfect world, a Ukrainian attack plane flies around Mach 1~1.5 then drops a JDAM ER at max altitude. The bomb deploys its winglets, a GPS guidance system (which was taught the coordinates of the target) kicks in, and constantly updates its own trajectory and movement based on information is constantly receives from GPS satellites.
It’s not a missile, lacking any kind of propulsion. It relies on the inertial force given to the bomb from the aircraft and the altitude of the bomb to carry the bomb the rest of the way to the target.
In this kind of “ideal” drop, a JDAM ER could strike a target as much as 70km away.
However, this kind of drop is considered entirely unrealistic for the Ukrainian Air Force. The Ukrainians are operating at a significant disadvantage in number of aircraft. The Russians also have numerous long range SAMs (Surface to Air Missiles) like the S-400 system that can engage any aircraft they can see.
Ukrainian Mig 29s and Su-24s are not stealthy aircraft, and flying at high altitudes, they are easily detectable on Radar. They can be intercepted or struck by SAM missiles before they can approach their target close enough to hit with even JDAM-ERs.
So, the tactic Ukrainian pilots have been using on the front line has been what is described as the “toss” method.
Ukrainian pilots fly at low altitudes to evade enemy radar detection. As they approach their maximum target distance, the pilot hits the afterburners and pulls the aircraft into about a 45 degree climb, quickly gaining altitude and speed.
While at that ascending angle, the aircraft will release the JDAM-ER then immediately bank hard into a turn so it loops and turn away from the enemy, zooming back down to low altitude while making an escape from enemy attacks.
This minimizes the amount of time the Ukrainian Aircraft is exposed in enemy radar, and allows for it to turn and make a quick get away, while releasing the bomb as far from the target as possible.
Because the winged bomb is angled upwards at the start of the release, the bomb achieves a far longer distance than it otherwise would. This is known as “tossing” a JDAM.
If a bomb is released at 2000 feet for a low altitude release, it can normally only get about a 15km-25km distance. However, from declassified tests by the Australian Air Force conducted in 2013, JDAM-ERs launched at a 45 degree upper incline at Mach 0.9 achieved effective ranges of 44km or more.
JDAM-ERs rely on the aircraft’s speed and trajectory to give it kinetic energy sufficient to reach its target—all other things being equal, the faster the aircraft is travelling at bomb release, the further it will go. Current generation JDAM-ERs can be released at speeds of over Mach 1.5, and depending on weight encumbrances Mig 29s may be able to attain speeds significantly greater than Mach 0.9. So it seems possible that Ukraine’s JDAM-ERs can achieve combat ranges of 45~50km, if not greater.
Ukraine already has HIMARS GMLRS missiles (range 70km), and will be getting the HIMARS fired 150km range GLSDB rocket powered glide bombs in September, so you may be wondering why I’m making such a big deal out of the JDAM-ER.
The issue is a 2000lb JDAM-ER is dramatically more powerful than either the GMLRS missile or the GLSDB rocket. A GMLRS rocket warhead contains 51lbs (23kg) of explosives. A Mark 84 2000lb General Purpose Bomb contains 945lbs (429kg) of explosives.
If the US Military was going to take down a bridge, GMLRS rockets would not generally be the weapon of choice. A GMLRS warhead simply lacks the explosive power to do that, and a GLSDB is even weaker. HIMARS launched ATACMs with its 160kg warhead is getting a closer to what you need but they’re off the table for now.
This is why the Ukrainian military hit the bridges over the Dnipro River repeatedly during the battle of Kherson without destroying them. GMLRS strikes merely degraded the road surface so it became very unstable and dangerous to cross, but never actually took down the Antonivsky Bridge.
This was certainly effective. It prevented larger convoys of Russian supplies from using the bridge, and truly heavy equipment (like tanks, self propelled guns, etc) were no longer able to use the bridge safely. The bridge occasionally “ate” heavily laden supply trucks.
The US military would likely turn to its workhorse heavy bomb, the Mark 84 2000lb bomb. For example, during the Battle of Mosul (Nov. 3, 2016), USAF hit the 5th Bridge with a single 2000lb bomb and knocked it out completely.
If you can pull off a JDAM-ER strike, you can do more catastrophic damage to a bridge than dozens of HIMARS strikes. Moreover, you don’t need to fire tens of millions of dollars worth of HIMARS rockets at a target—you can save those for other valuable targets.
Additionally, under the right circumstances, you could strike far deeper than a GMLRS rockets’ 70km range, provided the aircraft can penetrate Russian defenses closer to the target.
The key is getting the aircraft in and out alive from the weapon deployment area.
Russian Countermeasures and Ukrainian Counter-Countermeasures
Greatly simplifying things, Russia will rely on 3 primary weapons in an attempt to foil JDAM-ER attacks.
- Aircraft interceptors
- Surface to Air Missile Batteries
- GPS Jamming
Aircraft interceptors
The Russian air force has a large quantitative and qualitative advantage over the Ukrainian Air Force. The Ukrainian Airforce relies on the Mig 29 and Su-24 fighters as their workhorses, and most estimates believe they have no more than a few to several dozen remaining in operation.
The Russian Air Force is believed to have 200 or more Mig-31s and Su-35s (both superior more modern versions than Ukraine’s) and several hundred more modern fighters that are a match or newer than Ukrainian air force in modernity.
However, Russia lacks precision ground attack munitions, as well as any operational stealth aircraft—making their air force highly vulnerable to Ukrainian Surface to Missile attacks at high altitudes.
This is where Ukraine’s new Patriot Missile Batteries may have an outsized effect on the battlefield. A Patriot Missile Battery generally carries 2 types of ammunition—the PAC2 missiles that are used primarily against aircraft with a 160km (100mi) range, and the PAC3 Missile that is a specialized missile interceptor, with only a 40km (25mi) range.
Some people misunderstand this to mean a Patriot missile battery has only a range of 40km, but against aircraft, a Patriot Battery has an effective range of 160km.
For example, if you deployed a Patriot battery south of Zaporizhzhia city about 30km behind the front lines, you’d get this kind of coverage.
As you can see, it would be very difficult for Russian interceptors to fly CAP (combat air patrol) anywhere near the front line without getting shot down by a Patriot battery.
Unlike attacking aircraft which can hug the ground to avoid radar, interceptors are all but forced [Edit: see below, this was incorrect conjecture on my part] to maintain high altitudes—the high altitude is what gives them additional potential energy (in the form of elevation). When this patrol aircraft finds a target, it can dive. The interceptor can convert its altitude into greater speeds in dives, helping it catch up to their prey. An interceptor flying close to the ground will be significantly less effective, and would have difficulty catching an enemy aircraft from behind.
Patriot batteries and other long-range SAM batteries can provide an “umbrella” out of which Russian interceptors can be kept out. Bear in mind, many Russian radar based Air to Air missiles carry a 40km or so range, so Russian aircraft can stay out of this circle and shoot missiles about 40km into it. But simply deploying a Patriot Missile battery can help to keep Russian interceptors from dominating an air space with their sheer numbers.
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Additional comment from RO37:
Forbes reported that typical Russian CAP patrols take place only relatively deep within their own territory, and at extremely high altitudes to avoid the threat of Ukrainian SAMs and interceptors. However, based on Dancing Frogs’ comments below (that I found credible) this is not out of tactical necessity, but is a tactical choice on the Russians’ part.
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Comment from Dancing Frog that helped clarify some aspects of interceptor use by Russia pasted for additional/corrective information:
In the IADS simulations that I have been involved with, keeping one’s interceptors at altitude is not always necessary. Closing from behind on a strike package doesn’t usually happen. Most engagements begin as BVR shots from the front where the engagement envelope of SARH and ARH missiles is the greatest. While one does get a larger engagement envelope from being higher, radar functions better when one is looking up from below rather than from above even with modern look down-shoot down capability.
Also, it is easier to spot enemy aircraft from below visually when weather is not an issue. With the high rates of climb that most modern fighters are cable of, it is not that difficult to get into an advantageous position in the merge, so what you see are pop up attacks that occur after the BVR attacks where deconfliction with the covering SAM systems is difficult.
That means the Russians could fly CAP much closer to the front lines as long they remain below the radar horizon of the Patriot batteries and other Ukrainian long range air defense systems. The question would be, why haven’t they? The answer I think it is because with the proliferation of MANPADS and point defense systems in the Russian army and the Russian’s poor command and control systems, the danger of a blue on blue is high at all altitudes. Also, we really don’t know the effectiveness of the A50 AEW to provide coverage and coordination across the front.
Surface to Air Missile Batteries
The Russian military fields a variety of surface based anti-aircraft missile systems that operate at various ranges or “tiers.”
Tier 1 are the premier Russian SAM systems with the longest operational ranges, such as the S-400 system. Russia claims the S-400 can engage up to 400km ranges, but there are some doubts about this capability. At a minimum, 150km engagement ranges are probably realistic, possibly further.
Tier 2 systems are mid-ranged Russian SAM systems, namely variants of the Buk Missile launcher, generally with an engagement range of 40-45km.
Tier 3 systems are short range point defense systems, primarily designed to take out incoming missiles and bombs—often deployed to protect Tier 1 and 2 systems. Tor Missile System is one example, which can only engage targets within 12kms.
Before receiving JDAMs this March, Ukrainian pilots would have to fly to within visual range (3-4kms) of the target to drop an unguided bomb at their target, often bringing them within all 3 tiers of SAM range.
The capabilities of Russian SAM systems shouldn’t be underestimated. Leaked Pentagon papers indicated, and US officials later confirmed that Ukraine has lost 60 fixed wing aircraft to Russian SAM batteries.
One key advantage of the JDAM-ER may be that aircraft can fly in below radar detection range, fling the glide bomb at around 50km, quickly turn around without ever being in range to be engaged by Tier 2 systems like the Buk (which struggles to acquire radar signature of low altitude targets), requiring Ukrainian fighters to avoid only long range attacks from S-400 and similar systems.
Any strike will carry with it risks, but JDAM-ER gives Ukrainian pilots ways to minimize the amount of firepower than can be directed their way, and the highest possible chance to avoid return fire. A guided JDAM-ER will be far more accurate and precise than an unguided bomb as well.
One other weapon that provides Ukraine with a powerful means to strike back at SAM batteries is the AMG-88 HARM missile, which I will discuss more fully below.
GPS Jamming
One weapon that the Russians are deploying more commonly both as an anti-GPS guided weapon countermeasure, and a anti-drone countermeasure (which I discussed more fully in this prior diary) is the P340 Pole-21 broad spectrum jamming system.
The Pole-21 works by sending a powerful jamming signal across numerous spectrums, that help jam all kinds of electronic communications: wifi, drone control, radio communications and GPS. High tech electronic filters can be applied that help overcome this jamming, unless the jamming signal is activated “within a few kms.” when it is difficult for even sophisticated filtering to overcome jamming attempts.
The Pole 21 has reportedly proved to be a powerful weapon for Russia in drone warfare, presumably precisely because it may be being deployed near the front lines, to provide jamming at closer ranges.
Furthermore, the Pentagon Leak Papers indicate that the Pole 21 has been successfully used by Russian ground forces to scramble GPS guided munitions. Given the protections against jamming that weapons like the GMLRS or the Excalibur Round have, it seems unlikely the Pole 21 could jam them unless they are being deployed within 2-3 kms (if not closer) of the precision munitions targets.
These jamming efforts would similarly pose challenges to JDAM-ERs. Even if the GPS signal for the JDAM-ER is lost, the guidance unit will make approximations to continue guidance in absence of a signal, but accuracy is lost the earlier the signal is lost.
It’s notable that the US security packages in December and January noted the inclusion of AGM-88 HARM missiles, and likely are being included in more recent “precision aerial munitions” categories in recent packages. This makes sense because HARM missiles are the perfect counter to both SAM batteries and GPS jamming units.
AGM-88 HARM
Ukraine first started receiving HARM missiles from the US in Summer 2022, but deliveries appear to have stepped up since Ukraine began preparing for the next major offensive since around December 2023.
My hope is that Ukraine has been stashing these away for use in the Spring Offensive as much as possible, because these may be the “key” that unlocks both JDAMs and suicide drone waves as offensive weapons for a Ukrainian offensive.
The AGM-88 HARM missile has several varieties, but it appears the version Ukraine received is the “standoff” missile with 150km range and Mach 2.9 speed, weighing 381kg.
HARM missiles detect radar emitters and lock in on such a target’s location, striking it even if the radar switches off. This allows the missile to strike at various target that emit radar, such as surface to air missile batteries.
However, the HARM missile can also be programmed to lock in on GPS jammers. Way back in 1997, this capability was added to the AGM-88C HARM missile Block V upgrade, thus modern HARM missiles undoubtedly have this capability.
A tandem team of JDAM-ER launching Mig-29s, followed by a second wave of Mig-29s watching to see if GPS jammers or SAM batteries are activated may be an effective formation. The second wave can stand by at an even further distance (thanks to the 150km range of HARM standoff missiles). They can launch HARM missiles at any GPS jammers that dare to activate their systems in response to the attack, or any SAM batteries that activate radar to open fire.
Furthermore, HARM armed Mig-29s can be used to support a multi-wave suicide drone attack during an attack on Russian trench positions. Provided the current generation of Ukrainian suicide drones have electronic filtering capabilities, Pole-21 and similar systems need to be deployed very close to the front to be effective, likely within 1-2 kms max, if not right near the front lines.
This makes such jamming systems highly vulnerable to HARM missile strikes from long range by Ukrainian aircraft deep behind its own lines. If a first wave of suicide drones is knocked out by a jamming system, Ukraine can respond by firing HARM missiles at the jamming system, only to send a second, third, or successive waves of drones. If Ukraine aims to penetrate a 4-5 km stretch of trench line in a breach operation, it seems highly unlikely that Russia could position more than a small handful of systems at the most, making them vulnerable to attacks from HARM missiles.
I discussed how in the absence of jamming, multiple antipersonnel warhead suicide FPV (first person view) drones could be absolutely devastating to Russian static defenses here.
Depending on the version, Mig 29s have a carrying capacity of between 4000kg — 5500kg with 8 underwing hard points and 1 fuselage hardpoint. So a Mig29 might be able to carry 1 2000kg JDAM-ER and 4 to 8 HARM missiles for a ground attack mission. They can rely on Patriot batteries or other long range SAM support to keep interceptors off their tail, giving them broad abilities to strike enemy targets with relative impunity close to the front line—and under certain circumstances, far deeper into enemy territory.
For example, I believe that if the Ukrainians can advance to the Sea of Azov, I believe that the Kerch Bridge would be vulnerable to destruction by an attack by JDAM-ERs. Furthermore, with sufficient supplies of GBLDBs and JDAM-ERs, Ukraine could launch an interdiction campaign aimed at disrupting any attempts by Russia to supply Crimea by sea, and those supplies that make it through, by destroying the rail junction at Dzhankoi that lies only 45km from a hypothetical front line during a siege of Crimea.
I plan to make how an interdiction campaign of Crimea might play out in a future QE, but suffice it to say that HARM missiles and JDAMs (along with HIMARS) would play a major role.