Iran fired at least one ballistic missile with a warhead containing multiple submunitions as part of a particularly destructive barrage on Israel earlier today. Ballistic missiles loaded with cluster munitions present additional complications for defending forces, especially when it comes to intercept attempts in the terminal phase of flight. Readers can first get caught up on recent developments in the ongoing Israel-Iran conflict in our reporting here.
The Israel Defense Forces (IDF) Home Front Command says the warhead on the missile in question split open at an altitude of approximately 23,000 feet (seven kilometers) and released an estimated 20 submunitions, Emanuel Fabian of The Times of Israel posted on X. The submunitions, each of which contained some 5.5 pounds (2.5 kilograms) of explosives, were scattered across an area approximately 10 miles (16 kilometers) in diameter. Whether or not this is the first time Iran has employed a ballistic missile with a cluster munitions payload in strikes on Israel is unclear.
At the time of writing, the exact type of Iranian missile that carried the cluster munition warhead is unclear.
Iranian media outlets linked to the country’s powerful Islamic Revolutionary Guard Corps (IRGC) did share a video showing the launch of a Khorramshahr-4 medium-range ballistic missile (MRBM) earlier this morning, prompting speculation about its use. The Khorramshahr-4 is also sometimes called the Kheibar (not to be confused with Iran’s unrelated Kheibar Shekan ballistic missile), which is a reference to a seventh-century victory by Muslim forces over Jewish tribes. Iran’s Supreme Leader Ali Khamenei had also made a callback to that battle in the context of the current conflict in a social media post on Tuesday.
However, the Khorramshahr-4/Kheibar footage that is now circulating widely online is from a test in 2023, and there do not appear to be explicit claims from Iran about its use. As of yet, no other evidence has emerged of Iranian forces having employed these missiles, with or without cluster warheads, in its retaliatory strikes on Israel.
The potential combat debut of the Khorramshahr-4/Kheibar is something experts and observers have been keeping an eye out for, as it is assessed to be one of the most capable longer-range ballistic missiles in Iran’s inventory. The original Khorramshahr first emerged publicly in 2017, and it is assessed to be derived, at least in part, from the North Korean Hwasong-10, also known as the BM-25 Musudan. It is a liquid-fuel medium-range ballistic missile (MRBM) with a claimed range of around 1,250 miles (2,000 kilometers).
Iran has unveiled additional Khorramshahr variants since then, the most recent of which is the Khorramshahr-4/Kheibar, which made its public debut in 2023. At that time, Khorramshahr-4 was said to still have a maximum range of 1,250 miles (2,000 kilometers), but the possibility has been raised that it could have a longer reach. This is based in part on the underlying Hwasong-10/BM-25 design being an intermediate-range ballistic missile (IRBM), which the U.S. military has assessed in the past to have a maximum range in excess of 1,860 miles (3,000 kilometers). Khorramshahr variants could exchange some payload weight for extra range.
Khorramshahr-4 is understood to have the heaviest payload of any of Iran’s ballistic missiles, with it said to be able to carry a warhead weighing up to 3,300 pounds. Iran has also claimed in the past that Khorramshahr variants can carry multiple, smaller warheads.
In the past, Iran has also shown cluster munition warheads with designs that are in line, at least externally, with ones used on older ballistic missiles, especially variants and derivatives of its Shahab-3 liquid-fueled MRBM. The original Shahab-3 was based on North Korea’s Nodong series of missiles, which were themselves developed from the Soviet Scud family.
“Iranian media has for years advertised these sorts of cluster warheads as being able to ‘rain’ down bomblets against a wide target when dispersed at a certain altitude,” Behnam Ben Taleblu, a senior fellow at the Foundation for Defense of Democracies (FDD) think tank, told TWZ.
Iran has explicitly said it has fired Emad and Ghadr MRBMs, both of which are evolutions of the Shahab-3 design, at Israel in the past week. There is also clear independent evidence of this, visible in post-strike wreckage, including from the strikes earlier today.
Emad and Ghadr (sometimes also written Qadr) entered service in the mid-2010s and are both understood to be able to reach targets up to around 1,056 and 1,118 miles (1,700 to 1,800 kilometers) away. Iran has also developed an extended-range version of Ghadr that is said to have a maximum reach of 1,242 miles (2,000 kilometers).
In addition, Emad and Ghadr both feature maneuverable re-entry vehicles that detach from the main body of the missile in the terminal phase of flight, but they are generally assessed to be primarily focused on improving accuracy rather than evading enemy intercept attempts. Any kind of maneuvering re-entry vehicle does still present at least some degree of additional complexity for defending forces.
Adding cluster munition warheads to the mix would increase the potential of Iranian ballistic missiles scoring hits on area targets, and increase the overall area a single missile could target at once. On a basic practical level, adding this capability to missiles like Emad and Ghadr makes sense given the relatively low accuracy they are understood to currently offer when fitted with unitary warheads.
“[Sam Lair] and I estimated the ‘circular error probable’ (CEP) of the most accurate Shahab-3 variant, the Emad, demonstrated in Iran’s March 2024 missile strike [on Israel]. We estimated the CEP at ~1.2 km [just under three-quarters of a mile],” Jeffery Lewis, head of the East Asia Nonproliferation Program at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey, wrote in a post today on X. “That means whatever a Shahab-3 hits, Iran was most likely aiming at something else.”
“The warhead can likely be married with several [missile types], but to strike Israel they all have to be MRBMs,” FDD’s Taleblu also told TWZ. “In this, instance the missile body is less important than the warhead.”
As noted, ballistic missiles loaded with cluster munitions present additional challenges for defenders, especially if they cannot be intercepted before their warheads split open at higher altitudes. A very high altitude opening would also mean a more indiscriminate strike, which could be used to try to inflict as much damage as possible over a very wide target area, like a city. Typical cluster munitions are designed to release their payload at a specific height to saturate a more defined zone.
Layering ballistic missiles with cluster munition payloads in larger salvos with other types carrying unitary warheads might also help create a decoy-like effect to further overwhelm an opponent’s defenses.
With this in mind, while the specific circumstances are still unknown, it is worth noting that the interception rate during Iran’s particularly destructive missile barrage on Israel this morning was notably lower than what had been seen in previous salvos. A variety of other factors beyond the inclusion of cluster munition warheads could have played a role, as well.
As part of its retaliatory strikes on Israel so far, Iran also says it has been using other ballistic missiles, including Sejjil, Haj Qassem, Kheibar Shekan, and Fattah-1 types, that further add to the complexity of the overall threat picture. Sejjil is a two-stage MBRM that is among the heavier payload designs in Iranian inventory.
The Haj Qassem, Kheibar Shekan, and Fattah-1 are all solid fuel MRBMs. Compared to liquid-fueled ballistic missiles, solid-fuel types are generally faster and easier to launch, as well as safer to handle, reducing the total available time an opponent has to spot and preemptively target them before launch. Authorities in Iran have also explicitly touted these three missiles, all of which were unveiled in the past five years, as offering high terminal maneuverability and/or high peak speeds specifically intended to reduce their vulnerability to missile defense interceptors. The emergence of the Fattah-1 in 2023 was already seen as particularly significant, despite Iran’s dubious description of it as a “hypersonic” weapon.
“To put the significance of the Fattah in context, it is better to put aside Iran’s labeling of the system as a ‘hypersonic missile’ as the term can obscure more than it illuminates. Many surface-to-surface missiles achieve speeds within the atmosphere that cross the hypersonic threshold, that is greater than Mach 5,” Fabian Hinz, a research fellow for Defense and Military Analysis at the International Institute for Strategic Studies, wrote in 2023. “It is not speed alone that distinguishes the two main types of weapons known as hypersonic weapons – hypersonic glide vehicles (HGVs) and hypersonic cruise missiles (HCMs) – but also the ability to manoeuvre significantly during atmospheric flight, including at considerable cross-range.”
These are points TWZ regularly highlights, and you can read more about the unique capabilities that highly maneuverable hypersonic weapons offer here.
“Fattah is neither of these two classes of weapon, but a medium-range ballistic missile (MRBM),” but instead has a “second stage [that] incorporates the warhead, aerodynamic controls and a small solid-propellant motor with a moveable nozzle for thrust vector control (TVC)” that “resembles a maneuverable re-entry vehicle (MaRV) rather than a HGV.,” Hinz continued. “Both MaRVs and HGVs are capable of atmospheric maneuvering at hypersonic speeds. A HGV’s higher aerodynamic lift characteristics allow it to maneuver during mid-course flight, while a MaRV only does so for a short part of the flight in the terminal phase.”
“Iran attempted to overcome this limitation by mating a small TVC rocket motor to a MaRV, enabling exo-atmospheric maneuvering,” he added. “The IRGC maintains that this arrangement will help the missile evade both endo- and exo-atmospheric interceptors. It also potentially offers improved accuracy over longer ranges.”
Amid all of this, worrisome questions are already starting to emerge about the stocks of various types of anti-missile interceptors available to Israel, as well as U.S. forces in and around the country that have been helping to shoot down incoming Iranian threats since last week. As TWZ wrote in some of our previous coverage of the ongoing Israel-Iran conflict:
“The situation is something of a war of attrition over great distances. The question is will missile interceptors run out before Iran’s ability to launch its own missiles does? At this time it seems Iran is on the downside of that equation, but midcourse intercept capabilities are especially limited in quantity and degradation of that defensive layer would put more stress on the terminal defense layer, even if fewer missiles are fired.”
At the same time, Israel looks to have had significant success just in the past week in degrading Iranian ballistic missile capabilities. On Monday, Israel claimed it had destroyed a third of Iran’s long-range surface-to-surface missile launchers. Though Iran continues to fire ballistic missiles at Israel, and they continue to cause casualties and physical damage, the size and frequency of the salvos have been significantly smaller than what many expected to see in the event of the conflict that has now erupted.
Iran is also likely to be keeping at least some stockpiles of ballistic missiles, including more capable types, in reserve should the conflict further expand in scale and cope, especially if the U.S. military were to take a more direct offensive role. More capable missiles may be increasingly required for strikes on Israel as Iranian forces are compelled to move further east to reduce their vulnerability to IDF strikes.
Iran’s new use of ballistic missiles loaded with cluster munitions underscores that it still has capabilities that have not yet been fully brought to bear that could add new dimensions to the ongoing conflict.
Howard Altman contributed to this story.
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