Strategic Implications of North Korea's Enhanced Nuclear and Missile Capabilities

Narushige Michishita

This paper identifies important characteristics of North Korea's recent nuclear and missile developments and discusses strategic implications of those new developments.

1. Current Status

Estimates indicate that as of 2019, North Korea possessed 15 to 35 nuclear weapons. 1 In the 12 years following its first detonation test in 2006, North Korea conducted six nuclear tests, with explosion yield increasing steadily from less than one kiloton in the first test to 160 kilotons in the sixth test. Other North Korean efforts along that line included the miniaturization its nuclear weapons: the country has probably acquired the capability to mount nuclear warheads on ballistic missiles. The sixth North Korean nuclear test appears to have involved a hydrogen bomb, given the dramatic increase in explosion yield over previous tests. North Korea positioned its sixth test as "a test of H-bomb for ICBM [intercontinental ballistic rocket]" and "a very significant occasion in attaining the final goal of completing the state nuclear force."

North Korea possesses some 700 to 1,000 ballistic missiles, of which 45 percent are short-range missiles, another 45 percent are medium-range missiles, and 10 percent are intermediate- to long-range missiles. Many of those missiles are mounted on transporter-erector-launchers (TELs); estimates indicate that North Korea possesses as many as 100 TELs for Scud missiles, 50 for No Dong missiles, and 50 for Musudan missiles.

2. Improvements

North Korea continues to develop and flight test new types of missiles, and has steadily improved its missile technology and operational capabilities. According to Japan's Ministry of Defense, at the time of writing North Korea possesses or is developing 18 different types of ballistic missiles. North Korea has recently emphasized the development of solid-fuel missiles, intermediate- to long-range missiles, and submarine-launched ballistic missiles (SLBMs).

(1) Solid-fuel missiles

North Korea has developed KN-02 Toksa, the first North Korean ballistic missile with a solid-fuel propulsion system. The Toksa is a short-range ballistic missile with a payload of 500 kilograms and some 120-kilometer range, and is operated on mobile launchers. Its range has recently extended to 160 kilometers, and some believe that its circular error probability is 100 to 160 meters. The use of solid fuel has reduced the Toksa's launch preparation time to about five minutes compared to about 30 minutes for liquid-fuel Scud missiles.

In addition to the KN-02, North Korea is developing three other types of solid-fuel short-range ballistic missiles, the first of which is a short-range ballistic missile similar to Russia's Iskander, flying at low altitudes on irregular trajectories and highly capable of penetrating the missile defense shields of a target country. The second one is also capable of flying at lower altitudes and on more irregular trajectories than conventional ballistic missiles. The third is a short-range ballistic missile that North Korea dubs a "super-large multiple rocket launcher (= multi-rocket launcher)." Allegedly, this type can be launched in succession at an interval of less than a minute.

(2) Intermediate- and long-range missiles

North Korea is also developing intermediate-range ballistic missiles (IRBMs) capable of hitting Guam and Hawaii; and intercontinental ballistic missiles (ICBMs) capable of striking the US mainland. The Hwasong-12 has a maximum range of 5,000 km and is capable of attacking Guam. This missile uses liquid fuel, and can be launched from a wheeled mobile launcher, featuring considerable operational flexibility. North Korea has launched three Hwasong-12 missiles so far.

Second, the Hwasong-14 is a two-stage ballistic missile with a range of at least 5,500 kilometers. This missile falls into the category of an ICBM, but its firing range suggests that it can attack Hawaii but not the US mainland. North Korea has launched two Hwasong-14 missiles by now. Although it seems that the Hwasong-14 can be operated on a TEL, it was launched from a fixed missile site in the flight test conducted so far.

Lastly, the Hwasong-15 is a two-stage ballistic missile that boasts a range of more than 10,000 kilometers, depending on the weight of a warhead it carries. In that sense, this missile can be considered a full-fledged ICBM. North Korea had launched one Hwasong-15 missile so far.

(3) Submarine-launched ballistic missiles (SLBMs)

North Korea is developing SLBMs and ballistic missile submarines to carry them. First, the Pukkuksong is a solid-fuel SLBM with a range of over 1,000 kilometers. This missile is launched from the Gorae (or Sinpo) class submarine. Next is the Pukguksong-3, a solid-fuel SLBM with a range of about 2,000 kilometers, which will be carried aboard a new ballistic missile submarine currently under development. North Korea seems to be developing a land-based version of the same type of missile, the Pukguksong-2, which will be mounted on a tracked mobile launcher, as well as the Pukguksong-4 and 5. Incidentally, the Pukguksong-4 is analogous to the Pukguksong-3 but shorter in overall length. The Pukguksong-5 is a version of the Pukguksong-4 with a larger warhead.

A Gorae class ballistic missile submarine is now in service. With a displacement of about 1,500 tons and a maximum speed of 10 knots, this submarine, operated by a crew of 35, is likely to carry one Pukguksong-1 missile (with a range of more than 1,000 kilometers). North Korea is currently building another submarine of the same type. Secondly, there is a new ballistic missile submarine under construction, which, with a displacement of 3,000 tons, is estimated to carry three to four Pukguksong-3 missiles. Meanwhile, in January 2021, North Korea announced that its development of a "nuclear submarine" had entered the final review stage. However, it is not certain whether the term "nuclear submarine" refers to a nuclear-powered attack submarine, a submarine carrying nuclear missiles, or a nuclear-powered submarine carrying nuclear missiles.

(4) Characteristics

To summarize the direction of North Korea's missile capability improvement described above, North Korea is focusing on missiles with higher survivability, improved readiness and responsiveness, longer firing ranges, and a higher capability to penetrate missile defense shields. 2 The higher survivability has resulted from the enhanced mobility of land- and sea-based launch platforms. In addition, the solid-fuel missiles reduce the time required for filling fuel and, thereby, pre-launch vulnerability. Furthermore, by increasing the number of missiles deployed, North Korea is creating a situation where, if a certain number of its missiles are destroyed by enemy's attack, a significant part of them will remain intact.

Secondly, the deployment of solid-fuel missiles is instrumental in improving North Korean missiles' readiness and responsiveness. Test-launching different types of missiles from different platforms in various places has also helped to improve their operational readiness and responsiveness. Since 2014 North Korea has fired missiles from unprecedented launch points early in the morning or late at night using TELs; and it has launched multiple missiles simultaneously. It has also launched missiles from different launch points toward the same target. The fact that both wheeled and tracked TELs are now employed indicates that North Korea is attempting to strengthen its ability to operate missiles in a way less susceptible to weather and terrain conditions. North Korea is improving its capability to respond to hostile attacks and launch surprise attacks against the enemy.

Third, North Korea has been gradually developing short- to long-range missiles capable of striking targets from near to far––all of South Korea, Japan, Guam and Hawaii, and the US mainland. As a result, the country is already capable of carrying out missile attacks on targets in South Korea and Japan on a substantial scale, with more than 300 missiles each directed at them. However, its present capability to attack US territories is still at a limited level.

Fourth, to improve its missiles' capability of penetrating missile defense shields, North Korea has fired multiple missiles simultaneously for saturation attacks and launched missiles with lofted trajectories. It is also developing other missiles that can fly at low altitudes on irregular trajectories. Lofted trajectory missiles have higher re-entry velocities, making it difficult for the defender to intercept them. North Korea may choose to launch long-range missiles on lofted trajectories against high-value targets in its neighborhood in order to enhance the likelihood of successful penetration.

(5) Targeting

North Korea is also developing targeting strategies. In February 2016, the Supreme Command of the Korean People's Army (KPA) issued a statement listing Cheong Wa Dae––South Korea's presidential residence––and the "reactionary [South Korean] ruling machines" as the primary targets of attack, and the "US imperialist aggressor forces' bases for invading the DPRK [Democratic People's Republic of Korea] in the Asia-Pacific region and the US mainland" as the second group of targets. To strike the first target in South Korea, North Korea possesses and is developing sophisticated and diverse means of attack, including long-range artillery forces, multiple rocket launchers, and ballistic missiles. North Korea will likely use Scud-ERs and No Dong missiles against US bases in Japan, and Hwasong-12 missiles against Guam. Hwasong-14 missiles may be used against Hawaii and Alaska, while Hwasong-15 missiles against the US mainland.

The KPA Supreme Command declared that the DPRK possessed the means of "dealing fatal blows at the US mainland any moment and in any place," suggesting that it would be willing to attack both hard and soft targets in the continental United States.

3. Strategic Implications

There are at least seven important strategic implications of North Korea's enhanced nuclear and missile capabilities.

(1) Preventive attacks will become more difficult

Improvements in North Korea's nuclear and missile capabilities have made preventive strikes against North Korea even more difficult. Twenty-seven years ago (in 1994) the United States seriously contemplated a preventive strike against North Korea. Now a preventive strike against North Korea would be dramatically more difficult.

In 1994, North Korea's nuclear facilities were concentrated in Nyongbyon; today, they are scattered widely, and the target nations would have to destroy a large number of missile-related facilities. Moreover, the number of North Korea's nuclear weapons, estimated to be at most two in 1994, is now between 15 and 35. Weaponized nuclear devices are likely to be securely stored in several different locations, and it would be hard to wipe them out quickly. The US Joint Chiefs of Staff has reported that North Korea stores its nuclear weapons deep underground, and that a ground invasion would be the only way to identify and destroy those nuclear facilities. Since North Korea possesses large numbers of missiles, a full-scale attack would be necessary to destroy the majority of them. On the other hand, a US attack directed solely at North Korea's ICBMs would risk retaliation, since the North would likely retain capabilities sufficient to cause serious damage to South Korea and Japan.

An attack against the North Korean leadership, including Kim Jong-un, can also be an option. But since Kim Jong-un is cautious not to have his movements tracked by the United States and South Korea, such an attack would be anything but easy. South Korea's National Intelligence Service has noted that Kim Jong-un sometimes rides in the cars of his aides for fear of an enemy decapitation operation. In addition, any attack on the North Korean leadership, if attempted and failed, would risk inviting retaliation, including all-out war.

Consequently, to carry out a preventive strike, the United States would need full-scale mobilization and the use of force equivalent to that needed to fight a war. Specifically, the United States would need to be prepared to go so far as to implement the US-ROK Combined Operation Plan 5015 (OPLAN 5015) for preventive purposes. Clearly, fighting a major war today in order to prevent possible conflict in the future does not make much sense. Furthermore, about one-half of South Korea's population and one-half of the country's gross domestic product, along with some 200,000 Americans, are concentrated in the Seoul metropolitan area. Moreover, preventive strikes are illegal under international law––so viewed from any angle, the implementation of a preventive attack is unrealistic.

(2) Intensified military and diplomatic pressure on South Korea

The recent improvement of North Korea's nuclear and missile capabilities has put the country in a better position to deter retaliatory attacks from South Korea. As a result, North Korea can now exert even stronger military and diplomatic pressure on South Korea. Although North Korea ostensibly declares that the United States is the primary threat to it, in reality, the country is fully aware that South Korea alone could threaten its very existence. South Korea alone has the will and capability to absorb North Korea and unify the Korean Peninsula. For this reason, North Korea is likely to continue to take various military actions to keep South Korea on the defensive.

North Korea keeps pressure on the United States through demonstrative nuclear tests and missile launches. Yet, it has so far not taken any actual attacks against US forces resulting in casualties. Meanwhile, it has conducted low-intensity attacks against South Korea, which registered deaths and injuries––the sinking of South Korea's navy corvette Cheonan and the bombardment of Yeonpyeong Island in the Yellow Sea in 2010, the mine explosion in the Demilitarized Zone and the shelling in Yeoncheon County in 2015.

(3) Increasing risk of accidental military escalation

As North Korea is enhancing its nuclear and missile capabilities, the United States and South Korea are strengthening their defensive and offensive capabilities. The United States and South Korea signed the Operation Plan (OPLAN) 5015 in 2015, a much more aggressive and ambitious war plan than the previous OPLAN 5027. While OPLAN 5027 called for taking a defensive posture in response to North Korean attacks at the outset of war and then engaging in a counter-offensive, OPLAN 5015 adopted a "kill chain" concept calling for taking preemptive actions within 30 minutes following the detection of any sign of the launch of a nuclear weapon or a missile by North Korea. It is also said to contain the option of a decapitation operation against North Korean leaders who can approve the use of nuclear weapons, thereby preventing the use of nukes, as soon as any sign is detected that North Korea intends to resort to nuclear weapons. Reportedly, some South Korean military leaders have mentioned that OPLAN 5015 includes a plan to assassinate Kim Jong-un. OPLAN 5015 was allegedly used in the US-ROK military exercise Ulchi Freedom Guardian that took place in August 2015. In December 2017, South Korea inaugurated a special mission brigade (the so-called decapitation unit) with the mission of eliminating the North Korean leadership. South Korea plans to deploy a total of 2,000 ballistic and cruise missiles by 2022, which it hopes will enable it to eliminate 70 percent of North Korea's missiles and long-range artillery in a single day.

North Korea has reacted strongly to these operational concepts of the US and ROK militaries and South Korea's efforts to enhance missile capabilities. In 2016, the North Korean People's Army Supreme Command issued a "crucial statement" declaring that it would launch operations to suppress decapitation operations. It pointed out that the first target of the operations would be South Korea's presidential residence and other government organizations, and the second target would be the US bases in the Asia-Pacific region and the US mainland. It warned that if the US and South Korean special operations forces showed even the slightest movement, North Korea would take a preemptive action. The DPRK Asia-Pacific Peace Committee also warned that if the United States and South Korea show signs of launching decapitation operations, the Hwasong artillery units of the KPA Strategic Force would immediately fire rockets "fully tipped with nuclear warheads."

The various measures taken by the United States and South Korea aim to respond to North Korea's enhanced nuclear and missile capabilities. But those means employed are mainly offensive capabilities. In other words, offensive military capabilities are being strengthened on both sides, and the strategic environment is being created on the Korean Peninsula that is more prone to escalation. In particular, if North Korea continues to launch limited strikes against South Korea to keep it on the defensive, the possibility that South Korea would lash out in frustration would rise. If that happens, the situation could get out of control, increasing the risk of a serious military escalation.

In general, SLBMs are regarded as a nuclear asset with high crisis stability, as they are unlikely to be destroyed by the enemy. However, North Korea's SLBMs may become quite destabilizing in times of crisis. North Korea's ballistic missile submarines produce a lot of noise and are easily detected. A massive attack against the North Korean territory will be a prerequisite to destroy the country's ground-launched missiles. On the other hand, North Korean submarines are more vulnerable targets that can be destroyed by an attack underwater––political hurdles for such an attack are not high. There is even a possibility that if their ballistic missile submarines are sunk, the North Korean leadership may not immediately recognize the loss. Therefore, there is a good chance that both the United States and South Korea will be inclined to destroy those North Korean submarines in times of crisis or war. In this sense, North Korea's SLBMs are potentially destabilizing asset that invites military escalation.

The enhancement of North Korea's offensive capabilities against the United States, such as the Hwasong-15, will also raise the potential risks of military escalation between the United States and North Korea. The operational deployment of a meaningful number of Hwasong-15 ICBMs will enable North Korea to deliver significant strikes against targets on the US mainland. Since it is impossible to tell whether the deployed Hwasong-15 missiles are loaded with conventional or nuclear warheads (or biological/chemical warheads), the United States will have to act on the assumption that these missiles will carry nuclear warheads in times of crisis. In such a case, if the risk to the US mainland exceeds a certain level, the United States may launch full-scale preemptive attacks, including the use of nuclear weapons, to remove all of North Korea's offensive capabilities directed against it. Therefore, the deployment of ICBMs by North Korea will be so dangerous as to undermine crisis stability.

Although the arms race on the Korean peninsula is a cause for concern, it can produce some positive results. Recently, North Korea is becoming nervous about South Korea's successful development of new types of missiles, including SLBMs, and the deployment of a large number of cruise and ballistic missiles. Realizing that South Korea, far superior in terms of economic and industrial power, is advancing in earnest in the enhancement of missile capabilities, North Korea may have begun worrying about the possibility of losing the arms race with South Korea. If this is the case, North Korea may feel tempted to come an arms control negotiating table with South Korea, with a design to curb South Korea's military buildup.

(4) Increasing risk of a limited war

North Korea's improvement of its nuclear and missile capabilities will increase the likelihood that North Korea will consider a limited war as a viable option. If North Korea, the United States, and South Korea maintain a certain level of nuclear and missile capabilities, mutual deterrence will reduce the possibility of a full-scale war on the Korean Peninsula. But such a situation will, on the other hand, make it easier for North Korea to launch a limited attack on South Korea, assuming that such an attack is unlikely to escalate to a full-scale conflict. This phenomenon is called the "stability-instability paradox," which refers to that the diminishing possibility of a full-scale war will facilitate the occurrence of limited conflicts.

Specifically, the following scenarios may be conceivable. Suppose that North Korea fires 50 long-range artillery shells into the vicinity of Seoul. South Korea will retaliate by firing 150 artillery shells back into North Korea. To avoid the risk of major war, both sides will agree to a ceasefire. If considering the number of shells alone, the damage North Korea has suffered appears to be greater; the reality, however, is that highly populated South Korea, deeply integrated into the global economy, may have suffered a massive loss. If North Korea repeats such attacks, that would put South Korea in a highly difficult position.

(5) Constraining the US and Japan's commitment to the defense of South Korea

The improvements in North Korea's nuclear and missile capabilities will undermine the credibility of US and Japan's commitment to the defense of South Korea in the event of a conflict on the Korean Peninsula. Currently, the United States is allied with South Korea, and if war involving South Korea breaks out, the United States is ready to help South Korea and assist its defense operations. Then, Japan will also place some of its bases at US disposal, and Japan Self-Defense Forces will support US forces fighting for South Korea. Since Japan is now in a position to exercise the right of collective self-defense, the Japan Self-Defense Forces may not only provide logistical support but also take on more important combat missions like minesweeping.

However, since North Korea has come to possess a significant number of nuclear weapons and long-range missiles, the United States and Japan are facing more difficulties in supporting South Korea. In the event of a war in the Korean peninsula, North Korea will probably intimidate South Korea's allies by threatening to attack the United States and Japan, possibly with nuclear weapons, if they should decide to militarily assist South Korea.

Needless to say, the US nuclear advantage over North Korea will reduce the likelihood that North Korea will use nuclear weapons in the event of a conflict. Nonetheless, facing such audacious threats, the peoples and leaders of the United States and Japan will be obliged to make a difficult decision as to whether they should still support South Korea.

(6) Continuation of North Korea's brinkmanship diplomacy

North Korea's improved nuclear and missile capabilities will enable its continuation of brinkmanship diplomacy. The series of North Korea's actions between 2016 and 2019 suggests that Kim Jong-un strengthened his country's nuclear and missile capabilities first, and then embarked on major brinkmanship diplomacy vis-à-vis Donald Trump.

Also, there is the possibility that the acceleration of nuclear and missile development is part of Kim Jong-un's two-track policy aimed at advancing the country's nuclear development and economic development simultaneously. If that is the case, the two-track policy may be aimed at: (a) creation of a situation where North Korea can repel pressure from outside forces by first upgrading its military capabilities and then embarking on economic construction; (b) engagement in brinkmanship diplomacy made credible by its powerful nuclear and missile capabilities; normalization of relations with the United States and Japan; and acquisition of financial and technical assistance from them; and (c) setting of the stage for future economic construction by strengthening its nuclear capability so as to reduce its conventional forces and free up human resources and materials for appropriation.

(7) Emerging strategic linkage between the Korean Peninsula and the Taiwan Strait

The enhancement of North Korea's nuclear and missile capabilities would have a negative impact on the ability to defend Taiwan. Currently, the military balance across the Taiwan Strait is shifting in China's favor thanks to its rapid military buildup. The role of the US-Japan alliance in Taiwan's defense is becoming ever more significant; the 2015 Legislation for Peace and Security provides a legal basis for the two countries' armed forces to conduct combined operations for the defense of Taiwan. However, the US-Japan alliance is committed to ensuring the security of both the Taiwan Strait and the Korean Peninsula. If the allies' security burden vis-à-vis the Korean Peninsula grew, their commitment to the security of the Taiwan Strait would be adversely affected.

Of particular concern is the possibility that North Korea's improved nuclear and missile capabilities would make it difficult for the United States and Japan to devote the bulk of their anti-submarine warfare (ASW) capabilities and air and missile defense capabilities as well to the defense of Taiwan. For example, the ballistic missile-carrying submarines that North Korea is developing emit considerable noise, so their effectiveness as a nuclear deterrent is questionable—but they could serve as a means of diverting US and Japanese ASW capabilities. It would be a critical setback if, in a time of crisis, the United States and Japan were unable to commit their ASW capabilities to the defense of Taiwan.

In September 2021, North Korea announced that it had conducted a test launch of a cruise missile with a range of more than 1,500 kilometers. If that were true, North Korea would have the capability to attack Japan with the new weapon. Cruise missiles are slower than ballistic missiles, and easier to intercept; it is unlikely that North Korea would load precious nuclear warheads on cruise missiles. Nonetheless, the deployment of numerous cruise missiles would increase the burden on the Integrated Air and Missile Defense (IAMD) capabilities currently under development by the United States and Japan. In the past, potential threats from North Korea against Japan were limited to ballistic missiles, which could be dealt with by ballistic missile defense (BMD) assets alone. But the additional threat posed by cruise missiles would force Japan to take a much broader response, considerably increasing the country's military burden.

In the event of a future crisis or conflict in the Taiwan Strait, China would likely have North Korea create havoc on the Korean Peninsula in an attempt to draw US and Japanese forces away from Taiwan. In that context, it would come as no surprise if China were to decide to provide North Korea with military support to enable the North to effect the needed diversions.

(Vice President, National Graduate Institute for Policy Studies)

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