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The Logic Behind North Korea’s Recent Pukguksong Missile Test

North Korea test-fired a missile on the morning of February 12, a primary objective of which was to improve the survivability of its nuclear weapons and missiles. But it also seems that North Korea had other goals in mind when testing this new mobilized solid-fuel missile.

by Li Bin
published by
The Paper
 on February 15, 2017

Source: The Paper

North Korea test-fired a missile on the morning of February 12. Initial reports within South Korea indicated that this was a Musudan missile, which was launched from North Pyongan Province in the northwest of North Korea. The missile traveled along its flight path until it fell into the sea off of North Korea’s eastern coastline. Its total flight distance was 500 kilometers, and it also reached an apogee of 500 kilometers. The North Korean government released details regarding the missile test later on, stating that this was a Pukguksong-2 solid fuel missile, which is capable of vehicle transport. The launch point was identified as North Pyongan Province. The government also mentioned that a lifted trajectory was used in this missile test, in order to mitigate the threat perceived by neighboring countries.

Assuming that this missile actually did travel a distance of 500 kilometers, and that it actually reached an apogee of 500 kilometers, we can make a number of assessments regarding this missile’s capabilities. At the burnout point of the missile’s engines, its vertical speed would have been approximately 3,200 meters a second; its horizontal speed would have only been about 800 meters a second, and the total speed would have been about 3,300 meters a second. At the burnout point, the elevation angle of the missile would have been 76 degrees, which would have been a very steep angle of ascent. If the elevation angle at the burnout point was brought down to 45 degrees, the missile would be able to reach its maximum range of 1,100 kilometeres. The Musudan missile is known to have a maximum range of about 3,000 kilometers. Therefore, we can reach the conclusion that the missile used in this test was probably not a Musudan. It is more likely that the missile used in this test is what North Korea calls its mobile Pukguksong-2 solid fuel missile.

What is North Korea’s purpose in carrying out this missile test? It should be clear that North Korea has obtained a mobilized solid-fuel missile. Such missiles are easy to conceal, and are able to launch on short notice. Therefore, one of North Korea’s primary objectives in conducting this missile test was to improve the survivability of its nuclear weapons and missiles. The question remains, however, as to why North Korea would choose to fire at such a high trajectory. Was it actually their intent to avoid intimidating their neighboring countries? On the one hand, it is true that there are past examples of North Korea being deliberate when selecting the direction in which to launch their missiles in order avoid international condemnation. However, North Korea has not shown such concern in the past when test firing missiles with a range of 1,000 kilometers. It is difficult to imagine the Kim regime suddenly deciding to exercise greater caution in this regard. Therefore, it seems that North Korea had other goals in mind when testing this new mobilized solid-fuel missile.

A number of media outlets and politicians throughout the world have expressed the opinion that North Korea’s goal in carrying out this test was simply to provoke the international community. Such a conclusion, however, would underestimate North Korea’s determination in developing its nuclear weapons. In addition, this conclusion would not be able to explain exactly why the Kim regime decided to fire at such a high trajectory. If North Korea’s objective was simply to provoke, it would make sense that they would attempt to fire the missile as far as possible. However, the decision was made to fire the missile from the northwest corner of their territory at a very steep trajectory, which would cause the warhead to fall at a point that was relatively close to North Korea’s own territory. It is quite clear that this would not be particularly beneficial when it came to maximizing the provocative nature of the missile test.

North Korea has been working hard for quite some time to develop all aspects of its nuclear weapons program, which includes its missile delivery technology. However, the country has been facing a significant roadblock, in that it has been unable to test the atmospheric reentry capabilities of its intercontinental ballistic missile (ICBM) warheads. There are two main ways in which to conduct flight tests for intercontinental missiles. The first way is to fire these missiles toward the far reaches of the ocean and to allow the warhead to fall into the open sea. When conducting such tests, ships would first be sent to the approximate location where the warhead is expected to hit the ocean, in order to collect data as the missile reenters the atmosphere. However, North Korea would not be able to carry out naval observations of these tests while the international community is paying such close attention to its missile program. The second way to test intercontinental missiles would be to depress the trajectory of the missiles and reduce the ranges. This would allow countries with big territories to observe the missile flight tests on their own territories. But North Korea would be unable to carry out this method, as well, because North Korea’s territorial reach is still too narrow to allow for such observations to be performed from within its borders, even after the trajectory of the ICBM is depressed.

Even though North Korea is unable to test the atmospheric reentry capabilities of its intercontinental missile warheads, it has not given up on its missile development program. North Korea has already carried out a number of laboratory experiments, in which it has simulated a number of issues that might be encountered by its warheads upon atmospheric reentry. For example, they have used heating techniques in order to subject the warhead material to temperatures that would likely be caused by the friction of the atmosphere upon reentry. North Korea’s laboratory experiments have already been made public in media reports. These sort of experiments can allow North Korean researchers to gain an understanding of effects caused by individual factors involved. However, these researchers do not have confidence that they can thoroughly simulate the complicated nature of atmospheric reentry. Because of this, North Korea needs to carry out real flight tests and observe its warheads upon their reentry into the atmosphere.

The underlying problem for North Korea is that its national territory is too small. It is often the case that missiles leaving its territory are quickly propelled beyond a range that would allow for observation. If short-range missiles were used to carry out these tests, the reentry speed of the warheads would be too slow and the testing conditions would be overly simplified. Such tests would not allow for accurate conclusions to be made about the conditions that an ICBM would encounter upon reentry.

North Korea would therefore need to carry out a test that incorporates a missile that has a significant maximum firing range, which would allow for significant reentry speeds and would also be able to fall at a point that was not too far away from its national territory. This would allow North Korean researchers to observe the warhead’s reentry into the atmosphere. A solution that might be reached would be: 1) Fire the missile from one side of its territory toward the other side of the territory, thereby reducing the distance that the missile would travel over the sea, and; 2) Fire at a lifted trajectory, which would reduce the overall flight distance of the missile and also allow for the missile to travel at speeds comparable to an intercontinental missile upon reentry. The missile test that was conducted on February 12 meets both of these conditions: The missile was fired from its northwest corner toward the East, and the elevation angle of the missile at the burnout point of engine was 76 degrees.

If this accurately reflects the country’s thinking, then North Korea is not simply trying to use missile tests as a way of provoking its neighbors. It is trying to carry out a series of tests that are designed to evaluate the quality of its missiles when reentering the earth’s atmosphere, from which it hopes to be able to gain a better understanding of the physics involved when the warhead on an intercontinental missile is reentering the atmosphere. Last year North Korea test fired its Musudan missiles a number of times, most likely in order to carry out similar research. The international community now needs to consider how it will deal with North Korea as it continues to carry out such missile tests over the coming years.

This article was originally published in Chinese by The Paper (Pengpai News).

Carnegie does not take institutional positions on public policy issues; the views represented herein are those of the author(s) and do not necessarily reflect the views of Carnegie, its staff, or its trustees.