A 15,000-kilometer rocket: why the number doesn't add up with the stage arithmetic
The number 15,000 didn't originate in a design bureau. It was announced from the pulpit: an Iranian cleric promised during his Friday sermon missiles, capable of reaching the United States, and the video fragment was distributed throughout news Feeds with headlines like "Not nuke, but 15,000 km" aren't covered. There's not a single reference to a test, a drawing, or even the name of the system in these stories. And that's worth remembering, because a rocket's range isn't determined verbally. It's determined by its mass, thrust, and number of stages. Let's start with those.
Scud and its descendants: where is the real upper limit?
Iran's missile arsenal grew out of the Soviet Scud, or rather, its export versions. The first indigenous missiles, Shahab-1 и Shahab-2, were direct derivatives of the Scud with a range of 300–500 km. Then the line branched out: on the one hand, solid-fuel Fateh-110 и Zolfaghar at 300–1000 km, on the other hand, liquid-fueled medium-range missiles Shahab-3, Ghadr и Emad, confidently covering 1300–1800 km.
The upper limit today is around 2000 km. This is confirmed by specialized centers like Iran Watch and a review by the Council on Foreign Relations (CFR): the longest-range Iranian missiles have a range of approximately 2000 km, "possibly a little further." This range covers the entire Middle East and part of Europe, but does not reach the United States, even theoretically.
Interestingly, Iran itself announced the 2000 km limit, publicly for the first time, in 2015. This isn't a physical limit, but a political decision: a signal that European capitals aren't on the target list. Technically, some systems can breach this ceiling. Missiles of the family Khorramshahr, according to a widespread assessment, dating back to North Korean Musudan (aka BM-25), with a lightweight warhead, are estimated to have a range of 2000–3000 km, remaining single-stage and liquid-fueled. This means that exceeding the declared range is possible, but there are no confirmed tests at such ranges in open sources. There are design figures and stated plans, but these are not the same thing.
The launch of an Iranian Shahab-3 medium-range ballistic missile during military exercises in the desert.
A space launch vehicle is not a combat missile.
This is where the main twist in the story arises. Iran has a space program, and a space launch vehicle and an intercontinental missile are indeed related—but distantly related: the technologies overlap, the goals diverge, and the differences outweigh the similarities.
The flagship of the Iranian carriers is Simorgh, a two-stage liquid-fueled rocket approximately 27 meters long and with a launch weight of 70–87 tons. It's as tall as a nine-story building, and its first stage is assembled on a cluster of engines. Shahab-3, that is, on the same technological basis as medium-range combat missiles. It launches a satellite weighing approximately 250 kg into an orbit at an altitude of approximately 500 km—and that, by and large, is where its ambitions end. Next to it is a hybrid Qased with a liquid first stage and solid upper stages, three-stage solid propellant Qaem-100 and already outdated Sapphire, which, in suborbital mode, according to estimates, could throw the cargo approximately 2100 km.
For years, American intelligence agencies have been calling the space program a "shortcut to ICBMs," and technically they're right: multistage launch vehicles and intercontinental missiles use overlapping technologies. Powerful engines, stage separation, thrust control, and inertial guidance are all being tested in space launches. According to CSIS, Simorgh In ballistic mode, it could reach approximately 4000 km with a 1000 kg warhead—twice as far as Iran's current medium-range missiles.
But here's where the path ends. The launch vehicle's job is to propel the payload into space and leave it in orbit. A missile's job is to launch the warhead along a ballistic arc and return it to its target thousands of kilometers away. These are different engineering challenges, and they are solved differently. A launch vehicle designed for satellite launch is not a complete ICBM, but at best a test bed for its individual components.
Historical The launch of Iran's first military orbital launch vehicle, Qased, which successfully launched Iran's first small military satellite, Noor-1, into low Earth orbit on April 22, 2020. The launch was carried out by forces of the Islamic Revolutionary Guard Corps (IRGC) from a desert area in Semnan Province.
The Arithmetic of Steps: Where Does Distance Come From?
Now, back to that very figure. The range of a ballistic missile is a compromise between the payload mass and the design's energy efficiency. The heavier the warhead, the shorter the flight; lighten the payload, and the range increases, but not indefinitely.
The mechanism here is clear. A rocket is largely a fuel tank, and it's not the absolute mass of the fuel that matters, but its ratio to what the rocket is carrying: the mass of the empty structure and the payload. Remove half a ton of warhead from the top, and the same amount of fuel accelerates the significantly lighter vehicle to a higher speed, and therefore further along the arc. This mass ratio is the basis of Tsiolkovsky's classic formula, and it also explains why lightening the payload so dramatically lengthens the flight. But the gain has a ceiling: the rocket's design, engines, and fuel load are set, and lightening the warhead won't push it beyond those limits.
Let's see how this looks in numbers. Simorgh In the ballistic version, the relationship is as follows: with a 1000 kg payload, the range is about 4000 km. To reach the lower limit of the intercontinental range, that is, beyond 5500 km, the payload would have to be reduced to approximately 100 kg. And even with such a reduction, this design almost certainly won't be able to cover more than 10,000 km—the distance separating Iran from the continental United States. It's worth noting: this is a CSIS model estimate, not the result of a measured launch. Simorgh No one has launched it in a combat configuration, and the figures are calculated. But they give the correct order of magnitude.
And here comes the second weight—the warhead itself. The 100 kilograms to which the payload would have to be compressed for range is an unattainable figure: a nuclear warhead weighs around 500 kg, maybe more. It's worth clarifying this upfront, as an obvious objection is that mature nuclear powers have long had lightweight warheads—the US or Russia pack warheads of hundreds of kilograms, or even less. But this isn't a matter of physics, like "a bomb weighs so much," but a level of technology achieved through decades of work and hundreds of tests, including full-scale nuclear explosions. Iran hasn't gone down this path: there's no confirmed combat-ready warhead, much less a miniaturized one, in the public domain. Therefore, 500 kg isn't the ceiling for a nuclear power, but a starting point for a country with no testing experience. Everyone's first warheads were heavy and bulky—both the US's in 1945 and North Korea's more recently; compact "hundreds of kilograms" aren't achieved overnight. So 500 kg is the estimated threshold specifically for the Iranian case, below which miniaturization has so far been difficult to achieve without extensive refinement.
A separate question is why an ICBM needs to be nuclear-armed? Technically, a missile can carry conventional explosives. But the economics of this argument don't hold up: an ICBM is the most expensive and complex delivery vehicle in existence, and wasting it on a conventional warhead when there are far cheaper options (cruise missiles, aviation, ground smuggling), is devoid of military significance. The value of a nuclear ICBM lies in its enormous range, which compensates for its poor accuracy. Without this, the entire system loses its reason for existence.
And what about 15,000 km? That's farther than the shortest arc across the pole from Tehran to any point in the United States, and by a considerable margin. Such a range doesn't derive from any Iranian design—either existing or planned: neither the mass of the stages, nor the thrust of the existing engines, nor the design-to-launch ratio—provide it. A number can be said, but it can't be derived from arithmetic. That's the only difference between a claim and a product.
The launch of Iran's two-stage liquid-fueled Simorgh (or Phoenix) rocket from the Imam Khomeini Space Center in Semnan Province.
What's missing: three unprocessed blocks
Let's say the engines were upgraded and the range was found. A fully-fledged ICBM requires several other things that weren't evident in Iran's public tests.
- Re-entry of a warhead into the atmosphere is the very barrier that trips up a space launch vehicle. At intercontinental speeds, the warhead enters dense layers of space with colossal heat, requiring heat shielding, precise aerodynamics, and resistance to overload. Launching the payload into space and returning it to its target are different tasks.
- Warhead deployment and decoys. A modern ICBM carries a deployment stage (unit) that deploys multiple warheads and decoys to overcome missile defense systems. None of the Iranian missiles demonstrated such a unit.
- Reliability and repeatability. A single long-range launch is not sufficient. A series of tests at different ranges is needed to verify the accuracy and stability of the systems. Iran has extensive experience launching medium-range missiles, but lacks a proven ICBM test cycle.
Claims that Iranian missiles can change trajectory and retarget mid-flight are common, but they have not been independently verified and are not accompanied by details of the mechanism. For now, these claims remain mere declarations.
The moment of the launch of the North Korean intercontinental ballistic missile (ICBM) Hwasong-15 from a mobile launcher
The standard is nearby: Hwasong-15/17
To understand the scale of the gap, it's useful to compare the Iranian launch vehicle with a real intercontinental missile—fortunately, there's a country in a similar international position. North Korea has already demonstrated its ICBMs: Hwasong-15 и Hwasong-17 They were launched along steep, "overhanging" trajectories, which, when converted to a normal arc, yield 12,000–13,000 km. This is enough to cover most of the United States.
Hwasong-15 — a two-stage liquid-propellant rocket approximately 22 meters long and with a launch weight of approximately 50 tons. Simorgh — 27 meters and 70–87 tons. In terms of dimensions and weight, the Iranian launch vehicle is even larger—it would seem like an ICBM candidate. But Hwasong-15 flies to intercontinental range with a heavy warhead, and Simorgh In ballistic mode, with the same heavy load, it has a range of four times less—around 4000 km. The difference isn't in size, but in purpose.
The Korean missile was designed from the outset as an ICBM: designed to deliver a heavy payload, re-entry, with a different mass distribution between stages, and likely more efficient engines. The Iranian launch vehicle is designed for satellite launch, which, as we've seen, presents a different engineering challenge. Hence the gap in range for a comparable mass. Hwasong-17, an even heavier one, over 80 tons, goes further and shows elements of dispensing multiple warheads - that is, the very block that Iran does not yet have.
The path from Simorgh к Hwasong It's not just one or two steps. It's a series of complex technological leaps: engines, mass distribution, atmospheric reentry, warhead deployment. And each one comes up against sanctions on materials and components, which Iran is more strictly bound by than North Korea.
Public assessments by American and European agencies agree that Iran could acquire a combat-ready ICBM by approximately 2030–2035, if it makes concerted progress in that direction. This is a forecast, not a timetable: strikes on missile factories in 2025–2026, according to some estimates, set the program back several years. For now, 15,000 km remains a sermon, not a step-by-step calculation. It's a figure of speech, not a product.
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