North Korean ballistic missile tests over the past eight months have been a significant cause of concern in the United States and around the world. Recently, the U.S. has taken an increasingly aggressive posture, culminating in Donald Trump’s speech to the UN General Assembly, during which he threatened to “totally destroy North Korea” in defense of the U.S. or its allies. In the shadow of this growing crisis, experts both within and outside of government are debating whether using U.S. missile defense systems to intercept North Korean test missiles is the better response. Given the complex security situation, it is important to examine a brief history of missile defense to understand why the U.S cannot rely upon it to solve the North Korean situation.

What is Missile Defense?

Missile defense” refers to systems designed to shoot down ballistic missiles, the primary vehicle used to deliver nuclear weapons. A ballistic missile is a weapon with a high, arcing trajectory which is initially rocket-powered and guided, but which free-falls on its descent. These weapons can be short, medium, or long range (over 5,500km in the case of an ICBM), and their flight patterns have three phases:

  1. Boost: The missile is being launched and rockets engage. It is difficult to destroy the missile in this phase because it is relatively short and a defense system would need to be nearby to respond in time.
  2. Midcourse: At this point, the missile has left the atmosphere and the warhead separates from the body of the missile.  This is the largest window (about 20 minutes) within which to destroy the warhead.
  3. Terminal: The warhead re-enters the atmosphere at high speed, leaving little time before it reaches its target.

Although they are extremely complex, missile defense systems have a simple objective: use a missile to shoot down an enemy missile during a stage of its flight. They achieve this goal using the following three types of infrastructure:

  • networked sensors (including space-based) and ground- and sea-based radars for target detection and tracking;
  • ground- and sea-based interceptor missiles to destroy  a ballistic missile using either the force of a direct collision (called “hit-to-kill” technology) or an explosive blast to fragment the warhead;
  • and a command, control, battle management, and communications network providing the operational commanders with the needed links between the sensors and interceptor missiles.”

There are different types of missile defense systems, which differ based on the mode of transportation and at what point the system seeks to intercept the missile.

The concept of missile defense is certainly not new. The U.S. has been working on such technology since World War II when Germany developed the world’s first ballistic missile, the V-2. Since then, the U.S. has spent $189.7 billion on developing an effective missile defense. However, these systems were impractical for three reasons. First, they were, and still are, extremely expensive, which is why so few are produced and deployed. Second, for decades the technology simply was not advanced enough to reliably analyze and intercept enemy missiles. Taken together, these two factors directly limited the development of American anti-ballistic missile technology.

The third reason for limiting missile defense technology was strategic. The idea of being able to intercept nuclear missiles got a lot of attention during the Cold War, for obvious reasons, but missile defense was also seen as an escalatory capability. Joseph Cirincione, a well known expert, explained that this occurs because “an arms race in strategic defense systems fosters the proliferation of offensive missiles and the development of countermeasures to defeat the defense.” In short, if one side builds defenses, the other will seek stronger defenses and the capability to break through an enemy’s defenses. As a result, the arms race would quickly spin out of control. Perhaps even more importantly, extensively deploying missile defense could have ruined the deterrent of mutually assured destruction upon which the U.S. and the Soviet Union had based their arms race. Limiting anti-ballistic missile capabilities left both nations vulnerable and this in turn deterred them from launching an attack. The deterrent was cemented in the Anti-Ballistic Missile Treaty (1972) which limited the number of defense systems, their locations, and research and development. This treaty fell apart in December 2001 when the U.S. withdrew under the justification that the U.S. and Russia “no longer needed to base their relationship on their ability to destroy each other” and that the U.S. needed to defend itself from the use of ballistic missiles by “rogue states”.

Since then, both offensive and defensive missile technologies have improved significantly. Missiles are now faster, longer range, and capable of carrying more devastating nuclear and conventional payloads. In response, missile defense systems have become more sophisticated. They are no longer limited to the immobile, land-based systems of the Cold War, but are often dynamic, semi-mobile systems mounted on trucks — such as the MIM-104 Patriot system — or on naval cruisers as in the case of the Aegis Ballistic Missile Defense System. Additionally, the computer algorithms for analyzing a missile threat and calculating interception are more accurate.

As a result of technological improvements, missile defense systems have a greater role in current security issues. The United States’ increasing confidence in missile defense is evident in its decision to deploy systems to defend allies around the world. In Europe, the Obama administration implemented a plan entitled the European Phased Adaptive Approach (EPAA), which uses land and sea-based Aegis systems to defend NATO countries. In the Asia-Pacific region, the deployed systems are primarily positioned to deter and defend against North Korean aggression and are stationed in South Korea, Japan, the Sea of Japan, and Guam.

Implications of Missile Defense for the North Korean Crisis

However, despite outward confidence in missile defense, there is debate among analysts as to whether the U.S. is actually capable of shooting down a North Korean missile. Consider two cases: one in which it is likely that the U.S can shoot down a North Korean missile, and one in which it likely cannot. In the latter, the sort of recent escalation by the U.S President puts the U.S and its allies in danger of being forced to use the systems against an armed missile. Should the systems fail, lives would certainly be lost and the deterrence value of the systems would be greatly diminished, if not entirely eliminated.

In the former case, it is still dangerous to rely heavily upon missile defense because none of the U.S. systems, with the exception of the Patriot, have ever seen real combat. And although the Aegis and THAAD perform well in tests, it is still uncertain whether those test results accurately represent the system’s ability to intercept real threats. These doubts arose specifically because the most successful, took place during the day and targeting only one missile. An actual attack is unlikely to replicate either of those characteristics. In light of this, it is definitely unwise to threaten North Korea in such a cavalier manner because the U.S. could be forced to rely heavily on a relatively unreliable system.  Furthermore, this reliance on missile defense neglects long-term strategy. Even if North Korea tested missiles daily and the U.S. managed to intercept every one, there would need to be another plan of action for the United States to deescalate the situation and establish a status-quo. This can only be achieved through diplomacy.  

There seem to be three broad options for the United States as the North Korean crisis comes to a head. One is to preemptively attack North Korea with conventional or nuclear weapons. This is dangerous for a number of reasons. First, a preemptive nuclear strike would be reprehensible, likely kill millions of innocent people, and would entirely compromise the United States’ strategic and diplomatic position in Asia and around the world. A conventional attack would jeopardize the security of South Korea, particularly Seoul, which would likely endure heavy shelling while any conventional assault took place. Such an attack would inevitably lead to war, which in turn is estimated to leave 1 million people dead.

The second option is to deploy additional troops and defensive systems in order to strengthen the deterrence posture of the U.S. and its allies. While this option, unlike the first, is reasonable, it fails to address the heart of the problem. The nuclear threat does not just go away and an influx of troops prolongs a policy of inaction.

The third option is diplomacy. Angela Merkel called for a deal similar to the Iran nuclear deal in order to end the North Korean crisis. Although this seems unlikely, given Donald Trump’s position on the existing deal with Iran, such an agreement seems to be the best way to deescalate the crisis. While it is highly unlikely that North Korea would be willing to give up its nuclear weapons entirely, a diplomatic agreement could halt their development and allow for independent oversight, amongst other provisions.

There is no good solution to the North Korean crisis. But diplomacy and oversight is far more promising than the devastating conflict towards which we are currently hurtling.