Forum — From the December 2017 issue

Destroyer of Worlds

Taking stock of our nuclear present

( 4 of 8 )


By Theodore Postol

Those who touch us will not escape death! threatened one. a revenge attack of annihilation! promised another. strike the united states with nuclear thunderbolts! The language on the signs at a mass rally this August in Pyongyang, North Korea, was familiar: for decades, the pugnacious state has had a taste for hyperbolic threats, while its actual ability to strike the US homeland has lagged far behind. No matter how apocalyptic the rhetoric, Americans could take comfort in the fact that North Korean missiles weren’t going to rain down on the West Coast anytime soon.

A month before the rally, however — on July 4 — the regime launched a new ballistic missile, more sophisticated than the duds that used to plummet ineffectively into the Sea of Japan. The Hwasong-14 landed less than 600 miles away from its launch site, but analysts nevertheless predict that it could carry a small payload to Seattle. It remains unclear whether the new missile could successfully deliver a nuclear warhead, but at North Korea’s current pace, the technology could be in the not-too-distant future.

Officially, of course, we have nothing to fear from such attacks. After a much-touted test in May of the $40 billion Ground-Based Midcourse Defense system, designed to intercept intercontinental ballistic missile warheads in the near-vacuum of space, Jim Syring, then the director of the US Missile Defense Agency, declared that “we have a capable, credible deterrent against a very real threat.” In October, President Trump put his own estimate of the interceptors’ success rate at 97 percent.

There is little basis for this optimism: in the real world, the system is a flop. Despite being tested under highly choreographed and artificial conditions, the GMD has failed 55 percent of the time since coming online in 2004. In a real combat situation, it is highly likely the system’s failure rate would be considerably worse: not exactly favorable odds when nuclear annihilation is at stake.

Once fired, an ICBM goes through three distinct phases of flight before it reaches its target. The first phase, known as the boost phase, lasts between three and five minutes, after which the missile’s engines shut off. The warhead then detaches from the rocket and enters the midcourse phase known as free flight, cruising through space for roughly twenty-five minutes under the dual influence of gravity and momentum. Finally, there is reentry: the warhead plunges back into the dense lower atmosphere and, if all goes well, wreaks its havoc at ground zero.

Since the threat of a long-range attack first emerged in the 1950s, the United States has focused on ground-based anti-ICBM systems designed to intercept missiles during free flight. Nike-X (canceled in 1967 because of its exorbitant costs and ineffectiveness), Sentinel (canceled in 1969 after complaints about proposed launch sites in suburban neighborhoods), and Safeguard (canceled in 1976 after being operational at a single base for less than a year) all functioned according to the same principle.

The fundamental problem with these systems is that they are easily fooled. An interceptor homes in on its target by means of infrared sensors. To these devices, an incoming ballistic missile is virtually indistinguishable from other objects until the final two to three seconds before impact. During the rest of its trip, the interceptor sees only undifferentiated points of light. This makes the system vulnerable to simple countermeasures. An adversary might confuse the interceptor’s sensors by deploying balloons along with a warhead, or by breaking the trailing upper rocket stage into a multitude of fragments.

Even if the interceptor lucks out and happens to lock on to the proper target, it has to strike the warhead with extreme accuracy, often within a range of several inches. The smallest error leads to total failure. Given these weaknesses, a baseline of psychological comfort is really all a system like GMD has to offer.

So what might a workable missile defense system look like? To begin with, it would have to destroy its target during the boost phase, before the ICBM is able to exit the atmosphere and commence its smoke-and-mirrors routine. Assuming Pyongyang makes further improvements to the Hwasong-14, the defense system would have only four minutes in which to detect the launch, fire interceptors, and destroy the North Korean missile. The interceptors, in other words, would have to be based close to the peninsula. Ground-based missiles, in addition to being politically thorny, are immobile, and require considerable defenses of their own. Sea-based interceptors are more flexible and less vulnerable, but could fall victim to a submarine attack.

The most viable option, then, is to position our interceptors in the sky itself. A fleet of airborne drones, equipped with fast-accelerating interceptors, may be the only way to reliably prevent a successful North Korean ICBM attack. Patrolling at high altitudes, these drones can stay aloft for thirty to forty hours. Each can carry two anti-ICBM interceptors, which can also be used to shoot down satellite launches.

A drone-based program that is already under development at the Missile Defense Agency is reliant on aircraft designed to carry heavier payloads at higher altitudes. These drones have yet to be built, however, and are intended to be equipped with lasers that no one quite knows how to engineer. Given the urgency of the North Korean threat, we need a weapons system grounded in current technology rather than science fiction.

The vision of a panoptic drone army hovering over the Sea of Japan might strike some as dystopian, imperialist, or simply quixotic — to say nothing of the alarm it would cause in Moscow and Beijing. Handled sensitively, however, an air-based system would be a far more technologically effective way of shielding the West Coast from an incoming Hwasong-14. More to the point (assuming the Trump Administration desires a peaceful resolution), the presence of such a system might prod Kim Jong-un into pursuing a diplomatic solution to the current standoff. With its missile program rendered impotent, North Korea might be willing to approach the bargaining table with an eye toward de-escalation. Offense, as the saying goes, might actually be the best defense — and the only way to avoid a catastrophically destructive war.

More from Elaine Scarry:

Readings From the May 2004 issue

Acts of resistance

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