The North Korean nuclear crisis is escalating out of control. North Korean foreign minister Ri Yong-ho recently declared that US President Donald Trump’s comments about destroying his country were a “declaration of war”, and that, in response, North Korea would shoot down US bombers, even if they were not in its airspace. Last week, North Korean leader Kim Jong-un issued an even more dire threat: to conduct an atmospheric test of a hydrogen bomb in the Pacific Ocean, a nightmare scenario for the Trump administration.
If North Korea were to test-fire a live nuclear warhead using one of its ballistic missiles, it would seriously undermine the confidence of US allies – namely, South Korea and Japan – in America’s ability to guarantee their safety and contain the crisis on the Korean peninsula. Not to mention the fact that Trump would go down in history as the president who allowed atmospheric nuclear testing to resume on his watch, despite his best efforts.
So, how should the US respond?
One possibility that has been raised is to start shooting down the test missiles. But there is a very good reason that the United States and its allies haven’t been doing that: they probably can’t.
On August 29 and September 15, North Korea launched ballistic missiles on a trajectory that passed directly over Japan. This prompted the Japanese government to broadcast warnings on its nationwide emergency network, urging the populace to take cover.
The September 15 missile test passed 700km over the Japanese island of Hokkaido and landed in the open ocean, 3,700km from its launch point near Pyongyang. That distance is no coincidence. It proves that the US military bases on Guam are within range of North Korea’s missiles.
So why didn’t the US or Japan try to intercept this latest test?
The answer boils down to the fact that the capabilities of ballistic missile defence systems are limited, and almost exclusively effective in the areas they are placed to defend. Since North Korea’s two latest missile tests were targeted at the open ocean east of Japan, far outside the operational range of regional missile defence systems, the likelihood of a successful shoot-down was virtually zero.
The key to understanding this dilemma lies in the trajectory of the missile test. By the time the missile reached its apogee over Japan, it was already hundreds of kilometres beyond the reach of the Aegis missile interceptors that are deployed on US Navy ships off the coast of Japan. It was even further out of the range of the THAAD anti-missile batteries in South Korea and Guam, and far beyond the reach of Japan’s Patriot missile defence batteries, which are designed to engage short-range missiles during their terminal phase. The only realistic scenario for intercepting missile tests aimed outside the operating range of these systems is to position sea-based Aegis ships right off the coast of North Korea, near the origin of launch. This would theoretically enable the ships to intercept the missile during its mid-course phase. But as Kingston Reif, director for disarmament and threat reduction policy at the Arms Control Association, recently told The National Interest, it would be a “highly demanding task and entail a significant amount of guesswork, as the ships would have to be in the right place at the right time”.
In essence, Kim would have to tell the US exactly when the test was going to happen, provide the exact location of the launch site, the trajectory of the missile and the intended target of the test. That is not likely to happen. Some of this information could probably be deduced through intelligence gathering, but not all of it.
Even if the stars aligned and missile interceptors had a perfect shot at a North Korean missile, it is far from certain that they would succeed in hitting it. According to a 2016 report from the Pentagon’s Office of the Director of Operational Test and Evaluation, the regional/theatre ballistic missile defence system demonstrates a “limited capability” to defend the US Pacific Command, European Command and Central Command areas of responsibility for small numbers of medium- and intermediate-range threats (1,000km to 4,000km), and a “fair capability” for short-range threats (less than 1,000km range).
Although the success rate of these systems in testing has been high, it is far from perfect. They are also scripted for success. Almost everything about the incoming missile is known to the defender beforehand, and countermeasures, such as decoys, have never been deployed. That is a serious problem. A country that is technologically advanced enough to field sophisticated ballistic missiles can also be expected to deploy basic countermeasures.
The fact is that neither THAAD nor Aegis, the two systems that are the most relevant to the defence of Japan and Guam, have ever been used against a missile fired in anger. What would happen if they were to do so is a question better left unanswered.
Missile defence is an imperfect science. Even the US Pentagon says that it’s like attempting to “hit a bullet with a bullet”. But that rhetoric often fails to make it into the public narrative about missile defence. Only in April, Admiral Harry Harris, the US Pacific Command chief, told members of Congress that “If it flies, it will die”, referring to America’s ability to shoot down a North Korean missile attack.
This is dangerous. It creates an environment where the public, and key decision-makers who are easily influenced by the media, become overconfident in the abilities of missile defence systems to avert nuclear disaster.
The reality is far more grim. Missile defence is part of a carefully crafted system through which the US projects an image of invulnerability and strength. But that isn’t real. Missile defence is a last-ditch resort, only to be used as a plan B for damage limitation once disaster has already struck.
Attempting to shoot down a North Korean missile test, and failing, would shatter the illusion of invulnerability. America’s allies would be shaken to the core, and North Korea would be led to believe that its missiles are untouchable. Even a successful shoot-down would be problematic. It would generate the expectation that all of North Korea’s missile tests would be shot down, which the system would eventually fail to do.
Until America’s territory or that of its allies is directly targeted by a North Korean missile, the United States cannot afford to attempt a shoot-down. Much like the fairy tale of the emperor’s new clothes, missile defences are an illusion. By attempting to use the system, and failing, America would be exposing a harsh truth to the world. The emperor is in fact naked and exposed.
Will Saetren is a research associate at the Institute for China-America Studies, where he specialises in nuclear weapons policy