Cluster bombs have a bad rep and for good reasons. Yet, the cluster bomb concept has evolved from the dumbest of dumb bombs into a more targeted and discriminating weapon. One of these new cluster munitions in particular is incredibly complicated, heinously smart and ridiculously effective. They call it the Sensor Fuzed Weapon.

Traditionally, cluster bombs have been indiscriminate, wide area killers, both in their initial attack and via unexploded submunitions, often called 'bomblets,' that can look like brightly colored bouncy-balls or soda cans. This has led to the maiming and death of many innocent civilians and especially curious children around the globe. The delivery system for traditional cluster bombs have also lead to unintended effects of the battlefield. Until about a decade ago, cluster munitions relied strictly on 'gravity bombing' techniques that can be effected by wind and the stump-like aerodynamics of cluster munitions dispensers. Since combat aircraft often fly high to avoid anti-aircraft fire, traditional bombing runs would result in cluster weapon going wildly off course. This, paired with the large area these munitions effect have led to horrible, although unintended loss of innocent lives.


The Sensor Fuzed Weapon and other emerging 'smart' cluster bomb technologies aim to fix these deficiencies while also delivering an even heavier and more targeted punch to the enemy.

Without seeing it work in slow motion, you would think the concept behind the CBU-97 Sensor Fuzed Weapon, and the BLU-108 Sensor Fuzed submunitions it deploys, seems unrealistic, bordering on silly. Yet the truth is that this intricate weapons concept works incredibly well and has proven itself in combat to a stunning degree.

The idea behind the Sensor Fuzed Weapon goes something like this: Pack a handful of BLU-108 submunition 'cylinders' into a single 'delivery system.' In this case, let's limit the description it to the CBU-97 Sensor Fuzed Weapon housing, although cruise missiles and even artillery rockets can deliver the BLU-108 submunitions as well. The CBU-97 is very similar to the 'peel away,' drum-like cluster bomb canisters of decades past. Once dropped over an enemy formation, surface-to-air missile site or air base, the cluster bomb 'canister' will peel open at a predetermined height and out will pop ten BLU-108 submunition cylinders.

Once these 64 pound, 31 inch long submunitions are released, each will deploy a parachute, slowing their forward movement and orientating them vertically in relation to the ground. Then, a rocket motor fires and forces these cylinders into a slight climb, although at a distance it would look like the BLU-108s are hanging in mid-air. This rocket also causes the BLU-108s to spin rapidly.


As the submunition spins while almost hovering in mid-air above the target area, each BLU-108 cylinder will throw four individual sub-submuntions, known as 'Skeets,' from its body. Each Skeet is slung in a different direction at a 90 degree vector from the now empty BLU-108 cylinder. As these hockey puck-like Skeets fly through the air while rapidly spinning, a small infrared imager and laser ranging system activates on each one. The infrared seeker rapidly scans the ground below for an enemy vehicle or weapons fixture that it can recognize, while the laser ranger provides a ground contour map.

Trucks, armored personnel carriers and main battle tanks are not the only targets the BLU-108's Skeets can recognize and engage. Surface-to-air missile launchers, radars and even parked aircraft and support equipment can also be recognized and prioritized, giving the system a destruction of enemy air defenses (DEAD) and airfield attack capability as well as an anti-armor role.

Ok, so I know you reading this and asking yourself: "are you telling me these little flying pucks can recognize bad guys' vehicles and automatically decide whether or not to engage them while they spin freely through the air at high RPM?" The answer is unequivocally YES.

The Skeet's dual mode laser and infrared seeker compares imagery and dimensional information of what they 'see' with data stored in their memory banks. They can then rapidly classify what is a target and what is not. Since each Skeet was slung in a different direction upon deployment from the spinning BLU-108 submunition, there is little chance that more than one Skeet targets the same vehicle, aircraft or weapons fixture during the attack.

Once a target is selected, the Skeet fires off its 2lb explosively formed penetrator along with a fragmentation ring, sending a molten spear into the target along with a handful of dense shrapnel covering the area around it. The idea is that the penetrator kills the vehicle from top, where even main battle tanks are vulnerable, while the shrapnel kills who is inside (if it is a lightly armored target) and anyone in the targeted vehicle's immediate vicinity. If a target is not identified by the Skeet to engage, the Skeet will self destruct while still high above the ground. If this fails, a backup timer disables the Skeet after landing on the ground.

Once the Skeet is made inert, it is extremely resistant to exploding via tampering. This self-inert capability takes away some of the biggest arguments against cluster munitions: the fact that unexploded submunitions can harm bystanders a long time after an attack was originally executed. The result of which has left many men, women and especially children, limbless or worse.


Although the BLU-108 can be integrated into many delivery systems, the main one used is the aforementioned 'unguided' CBU-97 Sensor Fuzed Weapon. Like the ten BLU-108 submunitions housed within it, it is built by Textron Defense Systems. Those ten BLU-108s give the CBU-97 a total of 40 Skeets to dispense. These 40 Skeets can cover an area measuring up to 1500 feet by 500 feet. that is approximately 15 acres! Alternatively, the system can be programmed to open at much lower altitudes, which would apply its devastating effects to smaller, more target rich areas. The flexibility the CBU-97 offers makes employing it more of an artform than a science.

Although the BLU-108 and its CBU-97 delivery system were originally designed with low-flying tactical aircraft in mind, the weapon system can be fielded in mass aboard America's heavy bomber fleet. A single B-52H Stratofortress loaded with CBU-97s has the ability to take out an entire armored division. Before the CBU-97's development, such a feat would have taken many attack aircraft, big or small, and many hundreds of individual precision guided munitions, or possibly thousands of cluster bombs and dumb bombs to achieve.

Clearly, the BLU-108 and CBU-97 Sensor Fuzed Weapon pair represent a giant leap forward in precision air-to-ground weaponry, if not by the pair's volume of precision fire alone, than by the system's miniaturized autonomous targeting capabilities. Yet the CBU-97 and BLU-108 combo still have one massive drawback, for all the smart bomblets, or 'Skeets' it contains, the basic delivery system still remains 'dumb.' In other words, an aircraft still has to deliver the CBU-97 Sensor Fused Weapon dispenser using close-in, unguided gravity bombing techniques. In doing so, atmospheric conditions and human error can send the CBU-97 off course, to an area where no targets exist for it to engage at all. This is especially true considering combat aircraft crews would often have to deliver the CBU-97 from medium or even high-altitude to avoid enemy ground fire, and often times the target area would be formations of vehicles strung out linearly on a narrow roadway or ridge far below. A little to the left or to the right and the CBU-97's precious Skeets may end up frantically searching a field full of goats for possible targets. This is where the 'guided' Wind Corrected Munitions Dispenser (WCMD) kit comes in to play.

The WCMD adds an 'intelligent' tail section that contains maneuvering fins and an inertial navigation system to existing cluster bombs. Each tail-kit costs around $10k, a bargain when it comes to guided munitions. Part of the reason why the WCMD is relatively affordable is that although it is still considered a precision guided munition, a cluster bomb, by its very nature, doesn't have to be that precise. It simply has to deploy its deadly payload within a circular error of probability of dozens of yards (or about 85 feet officially), whereas the Joint Direct Attack Munition, which is a similar concept, existing as a tail attachment for 'dumb' high-explosive bombs, has a circular error of probability of about a dozen feet or less. In some cases laser guided munitions have an even a lower CEP than that.

The WCMD's comparatively larger room for error is due to the 'area attack' mission of cluster weapons and the fact that the WCMD runs on inertial navigation alone, with a GPS update handed over from the launching aircraft only right before the weapon's release release. Simply put, the WCMD doesn't have to be that accurate, as the weapon it facilitates is meant to cover a large area anyway. Still it is far more accurate than manual bombing.

The pairing of the WCMD and the CBU-97, which when mated together is called the CBU-105, is so incredibly useful and effective because it ensures that the weapon's Skeets are dispersed over the intended target area even when launched at long distances and high altitudes, far away from enemy fire. With the WCMD paired to a cluster bomb, being closer to and lower over the target does not improve the weapon's chances of being effective, as is the case with normal dumb bombs and unguided cluster munitions.

WCMDs can also be attached to standard, non-sensor fuzed cluster bombs, but the pairing of guided delivery with the BLU-108 submunition's individually guided Skeets allows for some pretty awesome effects on the battlefield. With proper real time intelligence, a large quantity of CBU-105s could be programmed to each open over an individual section of a target area, thus their Skeets can be evenly dispersed over that area. Conversely, they can be concentrated to where a very dense cluster of targets are known to be, decimating everything that lays below, with some targets getting multiple Skeet attacks.

For example, let's say a USAF RQ-4B Global Hawk with ground moving target indicator radar picked up a large enemy armored column moving on a highway towards allied forces. Once the convoy is detected, it is noted that on each side of the highway there are a series of small villages full of innocent civilians.

A single B-1B 'Bone' carrying 24 CBU-105s and six 1,000lb laser guided bombs is vectored into the area at high speed for a time-sensitive attack by the Combined Air Operations Center (CAOC). Guided by the coordinates and imagery data-linked from Global Hawk operators to the CAOC and back out to the B-1, the B-1's crew approaches the target area and starts taking synthetic aperture radar images of the highway and maps out generally where the convoy's densest formations are located.


The B-1 crew's plan is to first rapidly attack both the front and the rear of the armored advance using their 1,000lb laser guided bombs to trap the convoy, and to keep it from speeding away or retreating. The attack run is set and the lead vehicles, along with the roadway itself, are targeted with a trio of 1,000lb laser guided weapons. The targeted vehicles are vaporized in the attack and the roadway is deeply cratered.

The B-1, flying parallel to the highway at over 20,000 feet, then quickly targets the rear of the column, releasing three more laser guided weapons with similar results. The entire miles-long armored column is now largely trapped and in disarray, with escape routes both fore and aft blocked by a cratered roadway and flaming vehicles.

The B-1 then breaks off its attack and sets up for its final and most devastating strike. The bombardier takes a final radar snapshot of the now trapped convoy and programs each CBU-105 to open every 750 feet along the highway for maximum high-density effects. The B-1 then sets up for its pass at 25,000 ft, traveling up the highway that the convoy was just traveling on. The huge swing-wing bomber releases each CBU-105 in a rapid, computer timed salvo. With its bomb bays empty, the B-1 breaks off its attack run before having to overfly the armored column again.


The Wind Corrected Munitions Dispensers guide themselves over their designated dispersal coordinates and altitudes and their walls peel back in quick succession, releasing the BLU-108s sensor fuzed submunitions inside. The BLU-108 cylinders appear initially as tiny paratroopers floating down over the convoy, a few seconds later they turn into spinning rockets. 960 Skeets are released in a huge crescendo starting at the front of the convoy and ending at the rear of the convoy. Thunder and fire erupt above the highway as far as the eye can see, with the Skeet's penetrators firing into the most hardened enemy vehicles they see and their fragmentation sections sending hot shrapnel through the softer vehicles, material and personnel around their primary targets.

Meanwhile, the villages off of each side of the roadway lay totally untouched.

Within seconds, the BLU-108's hockey puck-like Skeets leave a large portion of the column's vehicles destroyed, with many of their crews wounded or dead. Those vehicles and personnel that did not receive fatal damage continues to be stuck among the burnt out wrecks, and susceptible to secondary explosions going off in trucks military vehicles laden with munitions and fuel. The cooking off of ammunition leads to a chain effect, decimating even more of the convoy without further attention from allied forces.


Now that the armored column is in chaos and largely destroyed, in fear that survivng forces may enter the surrounding villages, the CAOC orders in a flight of four F-15E Strike Eagles, each packing eight dumb, non-sensor fuzed cluster bombs, known as CBU-87s Combined Effects Weapons with Wind Corrected Munitions Dispenser tail-kits attached.

With the WCMD kit attached, the CBU-87 Combined Effects cluster munition is called a CBU-103. Although similar in appearance to the CBU-97 Sensor Fuzed Weapon, the CBU-87 does not contain BLU-108 cylinders and 'smart' Skeets, instead it contains 202 unguided 'bomblets' meant to sanitize large areas of land and decimate any soft targets and lightly armored vehicles on that land. The fact that it has a dud rate of between 5% and 10% makes it a very controversial weapon.

Each CBU-87/CBU-103 can be programmed to 'spin' at different speeds and at different altitudes during the submunition release sequence, which varies the size and density pattern of its bomblets over a certain area. A low altitude, low rate of spin release can result in an area 65ft by 65ft being totally decimated, but more commonly, a high rate of spin, high-altitude opening is used to cover an area the size of one football field wide by three long. This is roughly the size of a Nimitz Class aircraft carrier.

The F-15Es are data-linked the coordinates of the flaming convoy from the B-1 which is already exiting the area and each F-15E Weapon Systems Officer programs in an equal but different section of road for their guided cluster munitions to individually strike. Basically, the plan is to lay the four jets' payload out evenly over the entire convoy.


The Strike Eagles each make their attack runs from high altitude to avoid small arms and shoulder-fired missile fire. This run is meant to kill anything left alive and to destroy any 'lower priority' soft targets that the Sensor Fuzed Weapon's Skeet's or secondary explosions did not destroy. The F-15E's fly parallel to the highway and release their CBU-103s in a pre-programmed sequence based on the target pattern they chose. Like the also WCMD equipped CBU-105s before them, the CBU-103s guide their way to their targeted area autonomously. Once over their targets, each cluster bomb canister opens in quick succession a couple hundred feet above the stricken column. A spinning swarm of bomblets is sprayed out over the highway and the ground quickly turns into a blanketed maze of exploding, sparking, flying hot shrapnel.

Whatever or whoever survived the initial attack would not have survived the second. What just a few minutes prior was a massive division of armor hauling down a highway is now part of a near apocalyptic and horrifying scene of bend metal, burning flesh and thick black smoke, the victim of a whole new era of targeted, precise area bombardment.

Although the hypothetical scenario laid out of above sounds like something out of far-fetched action movie, it is not. Even without the fine tuning that the Sensor Fuzed Weapon has received over the last decade, and without the accuracy and standoff launch capability advantage that the Wind Corrected Munition Dispenser now offers, CBU-97s were shockingly effective during the open stages of Operation Iraqi Freedom over a decade ago:

Whether it be the CBU-87 Combined Effects Munition or the CBU-97 Sensor Fuzed Weapon, the addition of the Wind Corrected Munitions Dispenser and safer fusing technologies have changed the usability and tactical relevancy of the cluster munition concept.


One elite section of the air combat community that has taken an especially keen liking to the WCMD are the Wild Weasels. F-16CJ pilots are now able to sling cluster bombs at typically widely spread out surface-air-missile sites without having to literally fly 'down the chute' at them on a traditional gravity bombing run. This has enhanced the community's ability to prosecute not just suppression of enemy air defenses missions (SEAD), but especially destruction of enemy air defense missions (DEAD), literally destroying the surface-to-air missile site for good, not just shutting it down temporarily by firing a anti-radiation missile at it.

Like so many other successful guided weapons of the 2000s, the WCMD was to get enhanced range under the WCMD-ER ( ER standing for Extended Range) program. It worked by attaching a spring-loaded airfoil to the top of the munition, along with a WCMD-like tailkit. This was meant to enhance the WCMD's range to over 35 miles, which is a massive increase over the tailkit only WCMD concept as we know it today.


The WCMD-ER, when launched at higher altitudes and speeds, was aimed at allowing combat aircraft to stay outside the engagement rings of enemy SAM systems, while dealing them an absolutely devastating blow. One F-16CJ 'Wild Weasel' pilot described the WCMD-ER concept to me years ago, when the program was still in question:

This WCMD-ER is supposed to revolution how we approach DEAD and totally changes the risk equation for the enemy SAM operator. We will be able to target the WCMD-ER using the HARM Targeting System (HTS) and other 3rd party sensors via data-link. Instead of simply suppressing the threat and possibly getting a hard kill on an enemy radar emitter alone using the AGM-88 High-Speed Anti-Radiation Missile, we could obliterate an entire SAM site from a standoff distance using WCMD-ER. Game over.

Huge change in effects here, instead of just shutting a bad guy radar operator down so that he can fight another day and use his missiles with another emitter if we kill it with a HARM, with WCMD, and especially with WCMD-ER, we can kill his whole operation for good from a standoff distance. Just an awesome potential capability to have, especially in higher threat environments that are emerging where we can't get as close to the bad guy's SAMs as we may like to. It future-proofs the F-16 as a Wild Weasel platform for to a certain degree as well.

The WCMD-ER was cancelled after a short production run due to budgetary pressures, inconsistent results during testing, and the fact that America was bogged down in two crushingly expensive counter insurgency wars where standoff weaponry was just not a priority. That does not mean that the concept will not reemerge, and to some extent it already has with the submunitions dispensing version of the stealthy AGM-154 Joint Stand-Off Weapon (JSOW).

This stealthy glide missile is meant to take out highly defended targets and is integrated with the CBU-97s Sensor Fuzed Weapons and the CBU-87s Combined Effects bomblets. Still, it is an expensive, albeit extremely capable alternative to the simpler WCMD-ER, with over twice the defunct WCMD-ER's range, albeit with only about 60% of its payload.

Oddly, the US Navy and USMC, not the USAF, have purchased the highly successful JSOW, leaving F-16CJ Wild Weasels still without a true standoff area-effects weapon. The F-16CJ, especially if upgraded with an AESA radar for improved long-range ground targeting, could use Small Diameter Bombs in place of the WCMD-ER, targeting individual SAM launchers and emitters in a salvo attack. Still, this is an expensive and less capable means of sanitizing a large area at standoff distances than employing a single WCMD-ER or even a JSOW.

Another area where especially the BLU-108 Sensor Fuzed Submunition and its CBU-105 or CBU-97 delivery systems are said to be very effective is in the anti-small boat swarm mission. A single CBU-105, which can be guided precisely into positions close to, yet still outside the danger zone of allied vessels, could directly kill 40 individual small boats, with others also being destroyed from the BLU-108's unguided shrapnel components.

Literally, a 15 acre area of water could be instantly cleared of the enemy from a single CBU-105 or CBU-97 Sensor Fuzed Weapon, making it a potential panacea for the small boat threat that still doesn't have an 'area weapon' solution. If the CBU-97, or its WCMD guided CBU-105 cousin, or even a new smaller dispenser could adapted for carriage aboard a H-60 Seahawk helicopter, it could give everything from a Littoral Combat Ship to an aircraft carrier the ability to deliver rapid and devastating effects on an approaching small boat swarm.

It is amazing to think just how far 'smart bombs' have come over the last forty years, and especially in the time between Desert Storm and Operation Iraqi Freedom. With miniaturization of sensors, enhanced computing power and cutting-edge AI based software, the Sensor Fuzed Weapon took one of the most undiscriminating weapons of all time and turned it into one of the most discriminating. Paired with the WCMD delivery system, even an area weapon like the CBU-87 Combined Effects Munition can now be threaded into tighter areas than ever thought possible before. Although calling the CBU-87 a 'safer' weapon when it comes to duds and unintended damage to innocent civilians after its delivery would be inaccurate.


The self destruct and self inert capabilities of emerging submunitions, in comparison to highly volatile 'dumb' cluster bomblets, alleviates, at least to small degree, concerns about the unintended effects of using cluster munitions, which have historically been incredibly gruesome. Still, the shear volume of firepower that even these new 'smarter' cluster munitions provide, and like any weapon system, their inherent imperfections, will undoubtedly keep the cluster munition debate going strong well into the future. That and the fact that many of the other nations who have not signed the Convention On Cluster Munitions accord, will continue using extremely volatile cluster munitions that have not changed in design for many decades.

The ability for a single aircraft to do accomplish a mission that would have taken dozens, if not hundreds of aircraft prior to the advent of the Sensor Fuzed Weapon, and with great certainty and precision, is unprecedented.


In time, the Sensor Fuzed Weapon's unique discriminating abilities, and its WCMD delivery system, will most likely morph into even more dynamic submunition capabilities. Ones where taking out individual soldiers via large-insect sized flying explosives, capable of loitering above the target area for long periods of time, could become a reality. Or even a future where small nano-robotic mites are dropped using a WCMD-like dispensers over a convoy of enemy armor, their mission to destroy vehicles' electronics from the inside out without causing so much as a single explosion, may also become a real capability one day.

Both possibilities represent very different forms of future warfare, one that is highly deadly with an insect-sized delivery vehicle, while another aims at only harming material, leaving the human fighting force unaffected, although much less effective without their electronics-dependent weapons and vehicles. Additionally, cutting-edge cluster munitions like the Sensor Fuzed Weapon have paved the way for future area effects munitions that will have a strict time span of operational life before going inert, thus creating a 'safer' aerial denial system.


In fact, less deadly, more targeted cluster-like munitions are becoming very sought after capabilities for US mission planners. The CBU-107 Passive Attack Weapon being one of the latest iterations in this movement away from maximum destruction over a the largest area possible. It uses a WCMD delivery system and sprays out tungsten rods of various sizes at high-speeds over a limited area. Such a capability can be used for targeting anything where a large blast is not desirable, such as attacking chemical weapons depots or fuel storage facilities. The CBU-107 can even be used against soft structures in urban areas, such as antennas, without harming structures nearby.

The shadowy BLU-114, once a deeply classified submunition, also works at attacking an enemy's infrastructure without blowing anything up. In its case, it targets power distribution and generation facilities. Nicknamed the 'Soft Bomb' or 'Carbon Bomb,' this system deploys thin strings of carbon fiber coated with conductive material, which creates arches or electricity once it lands on an enemy's power lines and transformers. The result is a 'soft kill' if the installation's power generation capabilities, while allowing for repairs to be made later on.

With the rebirth of the American cluster munitions, and their potential sci-fi like future, the very idea of what a cluster bomb is and isn't will change. With their past traits of being one of the most inaccurate and non-discriminating conventional weapons of modern history giving way to a future where they may become one of the most targeted and precise killers ever devised. Possibly even one that works to harm enemy material alone and not human life at all.


Regardless of their potential future, American cluster bombs are clearly here to stay in their modern iterations, which are more capable, relevant and deadly than ever before.

Tyler Rogoway is a defense journalist and photographer who maintains the website Foxtrot Alpha for You can reach Tyler with story ideas or direct comments regarding this or any other defense topic via the email address