Who Can Stop North Korea's Ballistic Missile Launches?

What can be done about North Korea's constant ballistic missile tests? In 2017, as this issue of The Diplomat went to print, Pyongyang had carried out 18 ballistic missile launches. In 2016, it carried out 24 ballistic missile tests total. For news consumers across the world – and certainly in Northeast Asia – North Korea's missile tests are almost a fact of life. This year, they've occurred with metronymic frequency.

They aren't, however, completely normalized just yet and continue to be immense provocations. This is most acute for Japan, which has seen its territory overflown by two North Korean Hwasong-12 intermediate-range ballistic missiles (IRBM) in August and September. Just like North Korea tested the waters on landing ballistic missiles in Japan's exclusive economic zone with a Nodong test in August 2016, so did it test an IRBM over Japan in August to determine if the Japanese and U.S. response would be sufficiently tolerable to allow for continued testing.

These tests aren't just brazen provocations for the sake of provoking. North Korea's tests are never just tests for the sake of tests. Its ballistic missile tests have two important programmatic purposes. On one hand, with its older, short-range ballistic missile (SRBM) systems like its Scud-B, Scud-C, and Scud 2 missiles, North Korea increasingly carries out operational tests. It held a notable test to this effect in March 2017, carrying out a salvo launch of five ballistic missiles, with three landing in Japan's waters, to show that it was ready to fight a nuclear war. In any such war, North Korea would pursue a first strike in the Northeast Asian theater against military targets hosting U.S. troops and other assets in Japan and South Korea.

A second type of North Korean test – one that has been especially common in 2016 and 2017 – is the developmental test. These are the kinds of tests that the United States, the Soviet Union, and China used to frequently carry out in the 1950s and 1960s, when long-range ballistic missile technology was still new. These are also the kinds of tests that India and Pakistan carried out in the early-2000s, when their new nuclear forces were being established. For North Korea, developmental tests are a must-do. For its scientists, engineers, and even Strategic Forces missile crews, these tests allow for important technical feedback and permit for trial-and-error calibrations over multiple iterations with particularly troublesome missile systems (like the Musudan IRBM, which has now presumably been phased out after a series of failed tests in 2016).

Ballistic missile tests over Japan certainly have an important developmental purpose. They allow North Korea to expose its reentry vehicle technology to stress and heat conditions akin to what the missiles would experience in operational flight to targets at full-range. In the case of the Hwasong-12, such targets would presumably include Guam. Before it began overflying Japan in August 2017, North Korea would "loft" its long-range missiles – it would fire them at sharp angles almost nearly straight up to shorten their flight length considerably. Such tests with lofted trajectories would allow them to test the performance of the airframe, engines, and guidance systems, but not provide useful information on the reentry vehicle.

While North Korean ballistic missile tests are already highly provocative and frequent, they could get worse yet. On September 21, after North Korean leader Kim Jong-un released an unprecedented statement in the first-person lambasting U.S. President Donald J. Trump for his threat to "totally destroy" his country at the United Nations, North Korea’s foreign minister hinted that Kim is considering what once seemed unthinkable: an atmospheric nuclear test over the Pacific Ocean. This test would be the ultimate proof of a credible deterrent capability. If North Korea demonstrated once and for all that it could fly a compact thermonuclear warhead on its Hwasong-14 intercontinental-range ballistic missile to a range of some 8,000-9,000 kilometers and successfully deliver a nuclear airburst, the United States could no longer deny that it was at the mercy of North Korean nuclear weapons.

It's unclear that Kim would proceed with this kind of an option, given just how provocative it could be and how many things could possibly go wrong. For instance, an early detonation or in-flight failure over Japan could easily start a war. Nevertheless, one of the options that many observers call for as North Korea's missile tests undoubtedly grow more provocative is to shoot these test missiles down. The problem here – one that appears to be entirely ignored by many generalist commentators and op-ed writers on North Korea – is that the capabilities simply do not exist. Where they do exist, the United States and Japan would still need a great deal of luck to successfully intercept a North Korean IRBM or ICBM.

Neither the United States nor Japan attempted to shoot down North Korea's August and September Hwasong-12 launches. The official Japanese government rationale was that the missiles were determined to not pose a threat to Japan's territory. But what's more likely is that Japan and the United States simply aren't confident enough that the primary anti-IRBM platform – Aegis destroyer-based Standard Missile-3 Block IB interceptors – has a high enough probability of intercepting North Korea's missiles so far. A failure would come at great cost: it would prove to Kim Jong-un that his adversary's missile defense platforms are inadequate and show that Tokyo that Washington's alliance assurances are somewhat hollow. ICBMs are another matter entirely. The only anti-ICBM platform in the U.S. inventory is the Ground-Based Midcourse defense system in Alaska and California. This system can only engage ICBM targets en route to specific U.S. mainland targets; a North Korean ICBM launch into the Pacific would effectively be free to fly.

Ultimately, the consequences of all this are clear. North Korea will continue to get away with its developmental and operational tests of ballistic missiles. The costs of preemptive war, meanwhile, continue to be far too high and risky; any military action against North Korea would risk starting a devastating nuclear war – one that the United States would be forced to finish. With each test, North Korea will gain quite a bit too: it'll gain more knowhow and slowly chip away at the fundamentals of the United States' alliances in Northeast Asia.