Interceptor basics: A look at US missile defense weapons and stockpiles

Kelly, thank you so much for being here. A lot going on. We are in the 12th day of the Iran war. Operation Epic Fury continues. A big part of that operation are air defense capabilities of the United States, which include missile interceptors. So on a very basic level, I want to ask you, what are missile interceptors? I've heard them described as a bullet hitting a bullet

Well, first of all, thank you for having me. And great question. So what is an interceptor? I think the easiest way to understand it is essentially it's another missile that we launch to run into another missile and destroy it in the air

And those can hit ballistic missiles, drones, anything coming through the air

Yeah, we generally just design different kinds of interceptors for different kinds of threats. So you'll often hear about, say, something like that or the Pac-3 MSE. We tend to use those for ballistic missiles and for, you know, cruise missiles. You know, you might use something like NASAMs or an older Pac-2, which some of the Gulf states have, to try to hit, you know, a cruise missile that's flying at a lower altitude

And so some of those right now are being used more than others or some of those are more advanced potentially during what's going on right now

Yeah. So I think it's really about the threat environment. So if you look at what the Iranians have been sending up, they've sent up some, you know, a couple dozen cruise missiles. But for the most part, they've been relying on ballistic missiles. That was their big barrages, especially early on, were around ballistic missiles. And then the second thing was relying on these longer range Shahed drones, which are essentially one-way attack drones

Right. The drones that it seems like were deployed that killed the six U.S. service members

Yes. Reports have said that U.S. likely used between 100 and 150 THAAD interceptors and 80 SM3s in support of Israel during the 12-day war in 2025

150 of those would equate to almost 30 percent of the interceptor stockpile

So we do have a finite amount of these resources, correct? So we do have to be careful

Yes. And this is a serious issue One of the things I think that just to acknowledge is that it reflects in some sense years of procurement decisions So for the last 30 years the United States was very dominant in being able to control the airspace

And over enemy battlefields, we were basically able to operate without really serious concerns around aerial threats

So we didn't understandably invest as much in air and missile defense capabilities

And so those stockpiles, therefore, are only so large. There's been recognition increasingly of late that we need to invest more in that area

But the stockpiles are, you know, not they're fairly deep compared to many other countries, but they're not limitless

And the real challenge here is that you can go through them really quickly. So you mentioned the THAAD that we went through in the 12-day war

We're only procuring about 30 or so of those a year. So you can see how, you know, 30 is, you know, you're only getting 30 more a year

you're going through, you said about 100 to 150 in the 12-day war, the math on that, being able to

replace it becomes really hard. So are we in danger of running out right now? How close are we

to that slippery slope? I know we've seen a lot of headlines that say, you know, the United States

is going to run out of munitions. I think it's not quite the right approach to take such a broad

brush. What I would say is, in many respects, what we're doing is using up a lot of capabilities

capacity, particularly some really valuable munitions right now to be able to conduct this

operation. So will we have enough? Probably. Of course, it depends, you know, how long this goes

on and, you know, to what degree Iran in particular is able to continue to put, you know

missiles and drones into the air. But I think in all likelihood, we'll be able to get through this

operation. The problem is that you're buying down risk today in the Middle East theater for this

operation in creating long-term strategic risk because every missile or interceptor using today is not going to be available for another contingency, in many cases, for years

to come. Right. And it depends on the pace of the military campaign that would dictate how many interceptors were used the pace of the interceptor usage But in the event that the conflict extends for a very long time and the military campaign continues what would happen

if we do run out? What would that look like, the environment of conflict in the U.S. military

campaign? I think it's important to emphasize that particularly around this issue of interceptors

the United States and Israel are actively hunting the launchers for the ballistic missile

interceptors. And if they're able to destroy or disable these launchers, then Iran cannot get as

many missiles in the air. And it takes some of that pressure off. And they're trying to do some

of the same things with the Shahed drones as well. And they're claiming some success, particularly

around the launchers. If you were in a situation, though, whether it's this conflict or another one

where you really just don't have enough interceptors for the threat that you face, well, then you start to really have some acute operational and tactical trade-offs

So you may, for example, decide that you're not going to intercept every incoming missile

If you were, say, trying to defend an air base and you know that based on the trajectory, one missile is likely to hit a runway and another one is likely to hit where the fuel is stored, you may decide, OK, I'm going to allow that missile that's going to hit the runway

I'll let it hit the runway because I can repair the runway. Whereas if my fuel storage is blown up, it's going to cause a huge explosion and really damage the base

And so you'd have to make tradeoffs like that. The DOD has said that the rate of ballistic missile attacks and drone attacks from Iran has gone down significantly

which would seem to indicate that the rate of interceptors that the United States is using would, as a result, also go down

But is there a possibility that this is just a strategic repositioning on their part as the economic pressure mounts on the U.S.

on other Gulf countries with the closure of the Strait of Hormuz? Yeah, so I think it's important to, in particular, differentiate between the missiles and the drones

So, you know, the United States in Israel have been going after these launchers

The Israelis in particular have claimed that they destroyed at least 200 of them which would leave Iran with fewer than 100 So it possible that we been able to destroy the launchers I know that we also tried to destroy some of the sites where they had these missiles stored

Not clear entirely if those sites have been destroyed or they're just not able to access them right now

So there's the possibility they could gain access to that and then be able to put more missiles in the air

I think the drone one is more challenging and to even know where we stand

And there was a, you know, press conference that General Cain and Secretary Hegseth gave

on Monday. And Hegseth was asked about this specific question about, you know, how much progress

are we making against, you know, these Shahed drone threats? And he basically acknowledged in his remarks that we're relying on behavioral indicators

His answer was, well, we're clearly degrading their capacity because they're not getting as many in the air

And I would just say that, you know, he acknowledged battle damage assessment also exists, but that

It takes time, but the evidence is really more the numbers they're putting up in the air

But as you suggest, that's a problematic metric to use. It's possible that's because it is reduced capacity

It's also possible that they're adjusting their strategy. They're pausing to adjust a strategy

They could be trying to save up a number of these Shahed drones for a much larger barrage attack

you know they could be moving them closer to the strait of Hormuz to get into position because

they're preparing to close the you know close the strait and maybe to try to ambush any type

of minesweepers that come so we have to be cautious I think particularly around the drones and just in

general destroying the Shad drones is much more challenging in many respects they're smaller than

ballistic missiles they're somewhere between four and six assembly places in Iran for assembling

these drones, but you don't have to do it at one of these assembly factories. I mean, you could assemble a Shahed drone in your garage if you really wanted to

And a lot of the components that are used to make this drone, that's widely dispersed

across Iran. And I think we have to assume as well that the IRGC dispersed, you know, just simply

dispersed the Shaheds across the country for this reason