US Missile Defense Still Has a Long, Long Way to Go
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| Al Seib/Los Angeles Times/Getty Images |
A ground-based interceptor rocket is launched on May 30, 2017 from Vandenberg Air Force Base, California. The rocket from Vandenberg successfully intercepted and destroyed a target missile in space.
The United States successfully tested its interceptor missile defense system on Tuesday, essentially shooting an incoming missile out of the sky. An impressive technological feat to be sure, one the Pentagon likens to hitting a bullet with another bullet. But as proof that such a system could defend the US against a North Korean attack, it still misses the mark.
Think instead of the $244 million test as a competent recital, a choreographed display of US missile defense capabilities under optimal conditions. It leaves open the question of how the so-called Ground-based Midcourse Defense system would perform under real-world conditions—and how North Korea might respond to this latest demonstration of a system that US has spent almost two decades testing.
Missile Defense
The US first tested this descendant of Reagan-era “Star Wars” missile defense ambitions in 1999. It works on a fairly straightforward underlying principle: Hit an incoming missile hard enough to destroy it.
It does this by launching a rocket, which in turn releases a “kill vehicle,” a smaller device with four onboard thrusters and internal guidance systems that send it careening into the incoming missile. The kill vehicle doesn’t carry explosives, it just packs a punch.
Simple enough in theory. The reality is a different matter.
“The ICBM that’s incoming is expected to be going 15,000 miles per hour. The interceptor will be going on the same order, maybe a little slower,” says Laura Grego, senior scientist and global security specialist at the Union of Concerned Scientists. “You’re trying to line up these refrigerator-sized things in space at the same place at the same time. That’s a tricky thing to do.”
That explains the mixed results seen thus far. The US has tested the interceptor system 19 times since 1999, succeeding about half the time. The most recent test, three years ago, marked another success, but three prior attempts fizzled. That kind of success rate is troubling, given the meticulously managed conditions. “These tests are scripted for success,” says Philip Coyle, senior fellow at the Center for Arms Control and Non-Proliferation and former head of the Pentagon’s test and evaluation office. “What’s been surprising to me as that they have failed as often as they have in spite of that.”
The US Missile Defense Agency conducts the tests, and scripts the conditions carefully. “The defenders had significant information about the target ahead of time,” says Grego. “They know what it looks like, they know when it’s coming”—factors the Pentagon almost certainly won't know if North Korea or anyone else lets one fly.
The tests also don’t account for decoys and countermeasures that could throw off the missile defense system—tactics that include technology that confuses the launch-detecting radar systems or infrared sensors aboard the interceptor, or a simple balloon traveling alongside the incoming missile’s reentry vehicle.
All of which amounts to more caution than confidence, a note sounded even by the Pentagon. "Initial indications are that the test met its primary objective," said Vice Admiral Jim Syring, director of the US Missile Defense Agency, "but program officials will continue to evaluate system performance based upon telemetry and other data obtained during the test."
In other words? It worked today. But that doesn't necessarily mean it will work tomorrow—or when the US truly needs it.
A Growing Threat
Tuesday’s test comes amid mounting anxiety over the looming threat from North Korea. The Hermit Kingdom has escalated both its rhetoric and launch attempts in recent months, having test-fired eight missiles already this year. Although none of those missiles had the range to reach the US, the country is clearly working toward that goal. Yet Grego rejects the notion that the latest test was a direct response to Kim Jong-Un's saber-rattling. “These tests take a long time to prepare and to organize, both the time to prepare and to analyze the results afterward,” she says.
Of course, that does not mean such a test didn't send a clear message. “We are much more likely to convince Kim Jong Un not to ever try” striking the US, says Bruce Bennett, defense researcher at the Rand Corporation. Demonstrating the interceptor’s capabilities, Bennett argues, shows that the US would weather an attack well enough to deliver a devastating response. “We have really enhanced deterrence.”
Others remain skeptical. The US arsenal, after all, includes 36 missile interceptors with uncertain real-world performance. “If North Korea ever gets ICBMs that can reach the US, and they believe that our missile defenses work, they will just build more and more missiles so that they can overwhelm our missile defenses,” says Coyle.
Granted, the US could build more interceptors, but that creates its own geopolitical maelstrom. “If they make it too big, then they start to threaten the nuclear capabilities China and Russia has,” says Bennett. “We want potentially it a little bit bigger to deal with small countries like North Korea, to deal with accidents by an adversary, but we don’t want it so big that it can dwarf what China or Russia can pose, and therefore push them to taking action before we’ve completed the system.”
Think of it as a Goldilocks problem, except with nuclear devastation instead of bears.
So yes, the US missile interceptor system worked this time. But until it works every time, under real-world conditions, no one should read too much into a successful test. And even if the system achieves something approaching reliability, it’s important to consider the potential consequences. “You get the feeling that this is meant to reassure the US public and our allies that we’re doing something,” says Grego. “At the same time, if you’re overconfident about your system because you’re not clear-eyed about it, that can lead to riskier decision-making.”
Given the magnitude of those risks, it helps to see this test for what it is: a good step down a long, uncertain path.