Deterring North Korea: the view from Tokyo


As the tensions in the Asia-Pacific escalate further, the latest nuclear test performed by North Korea on the 4th of September, causing the equivalent of a 6.3 magnitude earthquake, renewed international concern over Pyongyang’s belligerence and its military capabilities. The blast, the biggest so far and considered to have been over four time bigger than the one that hit Hiroshima in 1945, accompanied the claim of having developed a hydrogen bomb.  Although the grounds for this claim remain limited, the test does show an unprecedented level of military sophistication that, coupled with the successful testing of an Intercontinental Ballistic Missile (ICBM) in July, suggests that great progress has been made towards the development of a missile that is able to carry a miniaturized nuclear warhead and directly target American soil.

During the past decades, Kim-Jong-Un has pursued Nuclear, Chemical and Biological programs with strong determination, in order to improve North Korea’s deterrence vis-à-vis what it perceives as existential threats. It has done so despite the widespread international condemnations and sanctions, which have ultimately been proven ineffective in impacting Pyongyang’s behavior or the escalating number of tests. Its regional neighbors, including South Korea and Japan, have been monitoring closely this increase in assertiveness and military capability, as it represents a direct danger to both countries. While the motives for North Korea’s aggression towards Seoul find their roots in decades of hostilities and a strong desire for reunification, Pyongyang and Tokyo are not in direct conflict. However, together with North Korea’s repeated shows of force, several factors reinforce Japan’s concerns: its geographic proximity to the peninsula and its key role in the multilateral alliances with other regional powers.

In 2017 alone, North Korea has launched 14 missiles, most of which have landed in the Sea of Japan, often in it Tokyo’s exclusive economic zone. These include the first successful test of an ICBM earlier on the 4th of July and culminate with a missile that flew over Japan’s northern island of Hokkaido before falling apart in the Pacific. This test was followed by Pyongyang’s declaration that the missile was “the first step of the military operation of the (North Korean military) in the Pacific and a meaningful prelude to containing Guam” and has been defined by Shinzo Abe as “an unprecedented, serious and grave threat”. Only twice before North Korea had fired a missile in Japanese airspace and both times it had done so with the excuse of a satellite launch. This is, however, a deliberate show of force, also reinforced by Kim Jong-Un’s threat to strike Guam, one of the biggest American bases in the region and key outpost for its power projection.

In this sense Japan, as a longstanding US ally and host of most of the American troops in the region, inevitably constitutes a central target of North Korea’s deterrence and retaliation capacity. The repeated missile tests in the past year have demonstrated Pyongyang’s capability to reach the entirety of the Japanese soil, which is characterized by highly populated urban conglomerates, such as Tokyo, hosting over 35 million people and representing one of the most likely targets in case of a Nuclear, Chemical, or Biological attack. Japan’s concerns over North Korea are not, in fact, limited to its nuclear weaponry, since its current delivery capabilities could be employed to launch a missile loaded with sarin gas. Several critical infrastructures on the archipelago, such as nuclear power plants, are also susceptible to conventional attacks, which, if successful, would have devastating repercussions as demonstrated by the Fukushima accident. Moreover, the distribution of US military personnel in Japan also represents a high-risk target, with over half of its deployed force of 50.000 stationed in Okinawa.

These considerations, coupled with an increasing military modernization by North Korea, are raising questions about whether Japan’s current defensive capabilities, namely the Ballistic Missile Defense (BMD), will be sufficient to deter or stop a North Korean offensive. As part of the BMD, Japan is equipped with two distinct interceptive layers: The Aegis missile defense system deployed at sea and the PAC-3 on land. These, however, do not provide an impenetrable shield and their effectiveness is decreased against attacks targeting multiple locations simultaneously. Japan also historically relies on the American nuclear umbrella as a fundamental source of deterrence, which has allowed Tokyo to maintain its pacifist defense posture based on the absence of offensive military capability. However, North Korea’s rapid modernization of both its ICBMs and nuclear warheads, inevitably puts a strain on the effectiveness of the nuclear umbrella due to the vulnerability of the US territory in itself to a retaliation. In the American perspective, Tokyo would not be worth the sacrifice of Los Angeles.

In the past months, North Korea’s repeated nuclear and missile tests highlighted these fundamental gaps in the current Japanese Self-Defense capacity, so much that it’s eroding Tokyo’s resilient opposition to acquire offensive capabilities, such as pre-emptive strike weaponry. The possibility of deploying cruise missiles was officially introduced in the parliamentary debate in March by Shinzo Abe, but acquired real salience only after the last missile launch. North Korea’s nuclear build-up is also fueling a longstanding debate over Japan’s non-nuclear posture in order to increase its independent deterrence capability against Pyongyang through the threat of nuclear retaliation. Although Japan is regarded as a global non-proliferation champion and has shown no concrete signs of willingness to breach its non-nuclear posture, it also maintains a “nuclear ready” status. This means that Tokyo still possesses operational and scientific capabilities that would allow the development of nuclear warheads in the short term, as a last resort in case of an escalation in North Korea’s actions from show of force to open declarations of war. Thus, it’s becoming increasingly clear how North Korea’s military adventurism and increasing aggressiveness plays a fundamental role in escalating the arms race in the region and fueling proliferation in the region.


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Caterina Perossa is an analyst at IB Consultancy. She holds a MSc in International Relation from the University of Bristol and a Bachelor in International and Diplomatic Sciences from the University of Trieste (Italy). Her research interests are in International Security and Strategic Studies, Arms control and Defence Policy-Making, with a specific focus on East-Asia and the Asia-Pacific.