Episode Notes:

The Islamic Republic of Iran test-fired a 2,000 kilometer (1242 mile) range ballistic missile, dubbed Khoramshahr 4, amidst regional tensions with Israel. To discuss the missile launch, its design and how far it flew, Jeffrey Lewis joined the WarCast. Jeffrey is a professor at the Middlebury Institute of International Studies at Monterey.

[:18] Intro

[:53] What was fired?

[1:48] A missile too fancy for its own good

[2:42] Payload

[4:02] Range

[5:41] Implications for the United States

[6:42] A link to the nuclear program?

Episode Transcript

Aaron Stein: My name is Aaron Stein and I am the Chief Content Officer at War on the Rocks. You are listening to the War Cast, the members-only podcast for what you need to know, now.

Hello. Welcome to War Cast. Today I'm talking to Jeffrey Lewis, who is a professor at the Middlebury Institute of International Studies at Monterey. The Iranians fired off a ballistic missile today. This comes amidst tensions in the Middle East, so I wanted to ask you first and foremost, what is it that the Iranians fired off?

Jeffrey Lewis: They fired off a new variant of an old missile. They call it the Khorramshahr-4, but you might recognize it as North Korea's Musudan or the old Soviet SS-N-6 submarine-launched ballistic missile.

Aaron Stein: One of the reasons I wanted to have you on this podcast is because you know the overlaps between these three missiles. So for people who are just hearing this, is this ... What is the legacy of this missile? And I know you've done some modeling. The Iranians say it can go to 2,000 kilometers. What say you?

Jeffrey Lewis: Oh, it can definitely go to 2,000 kilometers. This particular missile is a variant of an old Soviet submarine launch ballistic missile from the late 1960s, early 1970s that was quite capable, uses modern propellants, is actually kind of fancy. In fact, maybe a little too fancy for its own good. And so we've seen the North Koreans copy it and they struggled with their copy because the engine is a little bit finicky. The Iranians copied it as well via the North Koreans, and the Iranians seem to have a better success record. Maybe because they've made some design changes, but just maybe because they're like better at this than the North Koreans are.

Aaron Stein: So what do you mean when you say maybe it's a little too fancy for its own good?

Jeffrey Lewis: So the Soviets were putting these missiles on submarines, and so it was very important for the Soviets to limit the length of the missiles so it would fit in the submarine, and that led to a bunch of space-saving measures. The most important and strangest one is the engine itself is actually submerged in the fuel tank, which is an interesting bit of plumbing. It works. It definitely reduces the length of the missile, but that's a sort of delicate task. The Iranians actually in their statement today kind of bragged about that fact and talked about what a sophisticated design it was. I'd say it was just a dumb design that's probably worth more trouble, or is probably more trouble than it's worth, but beauty is in the eye of the beholder.

Aaron Stein: I think a lot of people are going to be asking what the size of the warhead is because the implication with Iranian ballistic missiles, I think this was signaling to Israel, I think that was at least the context of this launch, is that they have retaliatory capability that could fly as far as Tel Aviv. Again with your models, what's the size of the warhead?

Jeffrey Lewis: Well, the Iranians have said the warhead is about 1,500 kilograms, so that's a very large conventional warhead, not as big as some of the ones we've seen on the Korean peninsulas, or the Korean peninsula where the North Koreans and the South Koreans have gotten in a little bit of a measuring contest, but bigger than your typical Iranian payload. The engine is quite capable and so what I think we're seeing is that the Iranians are improving the missile, but they're stating the same 2,000 kilometer range, which is the limit that the supreme leader of Iran set for Iran's missiles. The engine itself is actually quite more, I think capable than that, and so I think there are probably two things going on. One is adding payload to keep it close to the range, and then I'm guessing probably a little bit of under reporting because ranges are ... Ah, they're tough to calculate.

Aaron Stein: So you preempted my next question, which is good. The 2,000 kilometer number always sticks out to me because that is the sort of self-imposed cap of range that the supreme leader put down on Iranian missiles. Is that 2,000 kilometer range, as you said, under reporting because they're sticking such a heavy warhead on it, and so this thing can actually fly a lot farther? Or do they have other programs that maybe flirt with that range that they're intentionally keeping under?

Jeffrey Lewis: I think the answer is yes to all of those possibilities. Range is a pretty funny concept. It depends, for example, the direction in which you fire something. If you're going against the Earth's rotation or with the Earth's rotation, the range will increase as your payload goes down. There are a lot of decisions you can make in terms of the trajectory you fly, and so range is a kind of general idea. I think it's definitely the case that we see the Iranians putting heavier payloads on in part because they are building systems that have a lot of thrust. I think also we see the Iranians doing a lot of work on solid propellant space launch vehicles, which will make wonderful missiles, if and when they decide to do that, but we've seen the Iranians shift really long range work into the space category so that it's at least consistent with what the supreme leader has said, even if I think a different supreme leader, or this supreme leader if he changes his mind, might eventually eliminate that restriction.

Aaron Stein: So what are the implications here for the United States? It's often sort of put out there either by critics of the Iran nuclear deal, which I think is up in smoke or the approach of the current administration is that previous agreements with the Iranians never dealt with ballistic missiles. Is this validating their concern or is the ballistic missiles just something that's a system that's already out of the bag?

Jeffrey Lewis: Yeah, I think ballistic missiles are like the weather. If you don't like it, it doesn't really matter what you like or don't like, you just have to deal with it. It's a situation where we have seen Iran invest really heavily in conventional ballistic missiles as a military capability. They're not the only country that does that. The Chinese have been leading the way on that. And I think when we look at what's going on in Ukraine, we see the Russians making a ton of use of long range precision fires, and frankly, that's something that the Ukrainians want in return. So I just think this is a modern military capability that everyone wants.

Aaron Stein: And is there a link to the nuclear program here, or is it separate? That's the final question.

Jeffrey Lewis: Well, there are always links because you can of course use these things to deliver nuclear warheads. Everyone forgets that nuclear warheads weigh less than conventional payloads. An Iranian nuclear weapon is not going to weigh rather anything like 1,500 kilograms, it's going to weigh a fraction of that. So I think that the desire to have conventional missiles is real. I don't think it's a cover for anything. I think that conventional missiles are awesome, and the Iranians want them for the same reason that the Chinese and the North Koreans and the South Koreans and the Japanese and the Taiwanese and the Ukrainians and the Russians, and everybody else wants them. At the same time, if you are going to build a nuclear weapon, you're definitely going to want to deliver it by missile, and these programs give the Iranians the option to do that.

Aaron Stein: Jeffrey, I have a million more questions, but we're going to leave it there. Thanks for joining the War Cast.

Jeffrey Lewis: My pleasure.