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A missile defense expert explains what North Korea’s latest test really means

Why the regime’s ICBM test is bad but not panic-inducing.

U.S. And South Korean Military Launch Missile Ballistic Exercise Photo by United States Forces Korea via Getty Images

North Korea successfully tested a missile on Tuesday that can carry a nuclear warhead and travel at least 5,000 miles in distance. The intercontinental ballistic missile test is the latest in a series of provocative acts by North Korea and the most significant development in the regime’s nuclear program in years.

It also crosses a dangerous threshold. Experts have long worried about North Korea’s nuclear program, but until now the regime has not demonstrated the ability to deploy a missile beyond their region. The missile fired on Tuesday shows that North Korea can at least fire a projectile capable of reaching Alaska.

How worried should we be? What did North Korea’s ICBM test actually prove? And assuming there’s nothing we can do to curb the regime’s plans, what are America’s current missile defense capabilities?

To answer these questions, I reached out to retired Army Lt. Gen. Patrick O’Reilly, a physicist who has worked in missile defense for more than three decades. He is the former director of the US Missile Defense Agency and currently a senior fellow at the Atlantic Council.

His assessment of North Korea’s test is that it’s a dangerous escalation but not necessarily an existential threat.

Here’s why.

Sean Illing

How alarmed should Americans be by this test?

Patrick O’Reilly

It’s obviously concerning, but from a military point of view, it's ridiculous that [North Korea] threatened someone who has so many orders of magnitude greater power than them. It's not a traditional military type deterrence scenario. They would never be able to deter the US — their technology is decades behind ours, probably many decades.

Sean Illing

So what’s the strategic logic here? Why posture in this way and risk dramatic escalation?

Patrick O’Reilly

I suppose they think this is about regime survival, that they have to demonstrate these capabilities in order to survive. That’s the only way I can understand their motivations for putting so much time and money and energy into this.

Sean Illing

North Korea isn’t an existential threat to the United States, but it’s still not clear to me what the appropriate level of concern is now that they’ve crossed this line.

Patrick O’Reilly

Well, in terms of hitting the continental United States, they have a very long way to go. But the United States has been doing the prudent thing for the past 13 years, which is deploying a system and steadily improving a system that is very well-suited for North Korea’s missile threat. It's not well-suited for a peer threat, such as Russia or China, but it is designed to deter North Korea in particular.

Sean Illing

What do you mean exactly? Why is our system well-suited for the North Korea threat?

Patrick O’Reilly

What I mean is that where we’ve located our missile defense technology and the kinds of capabilities we have are such that a relatively limited attack by North Korea could be neutralized. We have the ability to engage multiple missiles at any one time, and our recent testing showed that we can engage ICBM-class threats.

A massive attack by Russia or China presents an entirely different challenge — there really is no solution to that. But right now we can say that the probable success of an ICBM attack by North Korea, even if they had the capacity to launch it, is very much in question given their limited capability. Which why what they’re doing makes no sense from a deterrence point of view.

Sean Illing

Can you clarify what an ICBM is?

Patrick O’Reilly

The military has designated for years different ranges of missiles based on their velocity and the distance which they travel. ICBMs are those which travel at a velocity of anywhere from 5 to 10 kilometers per second and at a distance of at least 5,000 miles.

Sean Illing

North Korea appears to have successfully tested a missile that meets — or comes close to meeting — those conditions. What did their recent test show? What did it not show?

Patrick O’Reilly

Well, as far as what it showed, I'm not entirely sure. I don’t believe they reached the type of velocities I just referred to, which would classify the missile as an ICBM by military standards, but they did have a very long range, what experts might call “intermediate range.”

Now, I think their test had two stages, which is critical in terms of assessing performance. It seems they reached an altitude of close to 1,700 miles, meaning they clearly got it into space. And then they had a complete return back into the Earth’s atmosphere. Both of these stages are crucial testing points. But it’s important to note that while they did demonstrate reentry on this, we don’t know how successful that reentry was. Without directly observing it, we’re just guessing.

Sean Illing

How far away do you think North Korea is from developing a missile with a 10,000-kilometer range that could reach New York City?

Patrick O’Reilly

I would estimate, just by watching their progress, even with the most recent testing, that they're years away from something like that, and perhaps many years. Again, just like we're seeing now, for them to have any confidence in their system, they're going to have to do a lot of testing. That means their ability to surprise us with a capability like this is very unlikely — it’s just the nature of missiles and missile testing.

Sean Illing

If North Korea fired an ICBM at the US tomorrow, how confident are you that we could reliably intercept it?

Patrick O’Reilly

I've been retired for many years, but watching the approach we've taken to testing, I'd say I’m confident. Fairly confident because you can be assured that we have sensors in place to start tracking a missile almost immediately after launch, so there would be multiple opportunities to engage an incoming threat. Again, we can’t be completely sure, but I’d say the chance of success would be fairly high.

Sean Illing

Have these missile defense capabilities been rigorously tested? If so, what’s the success rate?

Patrick O’Reilly

Well, we’ve recently conducted a test involving an ICBM that was launched out of the Marshall Islands and the interceptor — basically the bullet we’re firing to shoot down an incoming missile — was launched out of Vandenberg Air Force Base (located in Central California). Now these distances are much longer and in much higher velocity than what the North Koreans just tested, and our test was successful. That’s in part because our sensors were in the right place for that test, but our sensors are also in the right place for a North Korea threat as well.

Sean Illing

That’s comforting to know, but there still seems to be a reasonably good chance of failure, given how difficult it is to essentially hit a bullet with another bullet.

Patrick O’Reilly

No doubt about it. A warhead is about the size of a desk, and you're trying to hit a desk from distances like 7,000 or 8,000 kilometers away. To hit a desk flying at upward of 8, 9, 10 kilometers a second, where if you're off by one second you miss by 10 kilometers or 12 kilometers, that's fairly amazing.

That we have systems that can react that fast and travel that far is itself incredible, but it's not only the spotting but also the tracking and the launching. You typically launch an interceptor and it’s over 10 minutes before it even gets close to its target. All of these distances are very hard to conceive. They're tremendously long, and the accuracy is extremely precise.

We've been conducting manned space flight for more than 50 years with those type of tolerances. When you get it wrong, unfortunately there's tragedies and fatalities. It's the same thing in missile defense. You don't have a lot of redundancy in your systems. They build them to be what’s called space-qualified hardware, so that it has extremely high reliability, and it's been tested to prove those reliabilities and the configurations are managed very closely. It's an extremely precise business. We proved that you can do it, but there are reasons the US is the only country in the world that can attempt these types of intercepts and be successful.

Sean Illing

How significant an escalation is this in your mind? As you know, immediately after the test the US and South Korea conducted a joint military exercise within 10 miles of the demilitarized zone. How close to a hot war are we?

Patrick O’Reilly

It’s extremely hard to judge. We still don’t know precisely how far along they are. Again, we don’t even know in what condition the warhead returned from space, and so it’s not clear how significant or urgent the threat is. But you can't deny that they're making steady progress. It's just that it's not, I would say, alarming progress as they move forward.

Again, they put satellites in space a couple of years ago. I'm sure they have the engine size and the staging capability, but given the kinds of tests they’ve run so far, it’s very difficult for them to have any confidence that what they’re shooting at is accurate.

So I think this is a serious concern that needs to be watched, just as we need to continue developing our defense capabilities, but we don’t need to panic just yet.

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