Japan has been considering building a “counterstrike capability” against the DPRK’s and China’s potential nuclear arsenals for quite some time. The new National Security Strategy and National Defense Strategy for Japan were drafted with this idea in mind by the Kishida administration.
It would appear that these counterstrike capabilities are similar to South Korea’s Kill Chain concept, which entails the ability to detect, track, and destroy enemy nuclear weapons and their delivery means (primarily missiles and aircraft) prior to launch. Even with strong missile and air defences, South Korea (ROK) and Japan have concluded that a nuclear attack from the Democratic People’s Republic of Korea (DPRK) could cause catastrophic damage.
South Korea will benefit greatly from Japan’s counterstrike capabilities, despite some opposition in Seoul, which could arise from any number of potential scenarios. The Republic of Korea (ROK) relies on rapid deployment of U.S. military forces in the event of invasion, but due to a lack of suitable airfields and ports in South Korea as well as a lack of readily available fuel, the United States must instead rely on airfields and ports in Japan to support these movements.
But North Korea is aware of this and may use nuclear weapons and missiles to pressure Japan into denying U.S. access in a conflict, thus limiting the number of U.S. forces available in the ROK in the event of a crisis.
An armed conflict between Japan and North Korea would result in one fewer nuclear weapon and ballistic missile that could have been used against the ROK if Japan had counterstruck. In the same way that the ROK Kill Chain can save the lives of tens of thousands of Japanese, the destruction of even a single DPRK nuclear weapon by the Japanese could do the same.
When it comes to North Korea, the fates of the two neighbours are inextricably intertwined, and the ROK Kill Chain and Japan’s counterstrike capability can reinforce one another.
Suppressing an Assault
The limited capabilities of South Korean and Japanese missile and air defences could be overwhelmed by hundreds of North Korean missiles and drones. Since the Kill Chain and counterstrike capabilities could reduce the number of North Korean missiles the ROK and Japan have to defend against, this would lessen the likelihood that their defences would become overwhelmed.
Because of the disparity in conventional firepower, North Korea is likely to rely on a nuclear first strike, but both of these ideas can be implemented in advance to prevent this. Combined, the capabilities of the ROK and Japan could significantly increase deterrence pressure on North Korea by lowering the likelihood of a successful DPRK nuclear preemptive attack.
However, North Korea would likely store some nuclear weapons underground for use as a last-gasp survival threat, so the Kill Chain and counterstrike capability may not need to be executed preemptively. Multiple missiles accompany each transporter erector launcher (TEL) in the North (PDF).
Thus, perhaps 80% or so of North Korea’s missiles could still be hidden underground somewhere without a TEL if the country attempts a first ballistic missile launch. If the DPRK’s underground stockpile of nuclear weapons and missiles is discovered, South Korea and Japan may be able to end the conflict without further provocation. This has the potential to increase the difficulty of launching an attack from North Korea.
It’s possible that North Korea is deterred from taking such risks because Pyongyang knows that Seoul, Tokyo, and Washington could effectively retaliate to any limited attack on the ROK or Japan.
To effectively counter North Korea’s nuclear and missile threats, Japan needs reliable intelligence gathering systems. It’s possible that those systems will gather vital intelligence that will be of use to both the ROK and the USA.
As much as the ROK and Japan are focused on the nuclear threat from North Korea, they are also worried about the rise of China. Neither nation is interested in starting a war with China, but they also don’t want Beijing to use nuclear threats as a tool to intimidate them. Because of this mutual fear, both nations may find the Kill Chain and counterstrike capabilities useful when negotiating with China.
Destinies Intertwined
Since all of North Korea is considered part of the South by the ROK constitution, a Japanese counterstrike would be hitting South Korean territory even though the ROK does not control it, which has caused some South Koreans to worry about the Japanese ability to launch a second strike.
In the event that Pyongyang attempts to conquer the South, Seoul will likely reclaim this territory and thus has reason to worry about any damage that may have been done there. Moreover, if Japan launches a counterstrike, North Korea is likely to launch attacks on both the ROK and Japan, drawing the South into the war.
But the same can be said about the Republic of Korea carrying out its Kill Chain: doing so would likely lead to escalation from North Korea, drawing Japan into the war as the North attempts to thwart U.S. force deployments to the South.
Working together, South Korea and Japan can maximise the effectiveness of their Kill Chain and counterstrike capabilities. Coordination may need to take place now, in times of relative calm, because the implementation of these systems is likely to be time-sensitive.
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If either of these plans is implemented, the United States could join in, providing both vital intelligence and substantial force capability to eliminate the nuclear threat posed by North Korea. Pyongyang’s use of nuclear weapons would also trigger the U.S. nuclear umbrella offered to the Republic of Korea and Japan, which could be coordinated.
North Korea might be deterred more effectively by a combined effort of the South Korean Kill Chain and the Japanese counterstrike capability. As Pyongyang realises that its efforts to militarily dominate the ROK are unlikely to succeed, these measures may be more effective in discouraging Kim Jong-un.