Nuclear North Korea and Japan: The INF Option
U.S. Army photos by Sgt. John L. Carkeet IV, U.S. Army Japan

Nuclear North Korea and Japan
The INF Option

by Richard Lawless
December 14, 2020

As North Korea’s missile capabilities continue to grow, Richard Lawless discusses options for the U.S.-Japan alliance to address the threat posed by North Korea to the United States and its allies. He concludes that the only way a U.S. conventional and nuclear deterrent can be made credible for Tokyo is to deploy intermediate-range nuclear force (INF) systems to Japan.

The political dynamic of Northeast Asia has been altered forever by a belligerent North Korea armed with a credible nuclear weapons arsenal. Complementing the weapons themselves is the ability to deliver these devices in war-initiating scenarios on the Korean Peninsula, regionally and beyond. Civilian targets in Japan and South Korea, as well as U.S. military bases in those countries and Guam, are now held at risk. More recently, the U.S. homeland found itself threatened by North Korean invective backed up with the promise of a real capability.

This commentary examines the evolving threat posed by North Korea to the United States and its allies and discusses a range of options for the U.S.-Japan alliance to address this threat. Among the many options considered is the deployment of intermediate-range nuclear force (INF) systems to Japan.


Today’s reality is that North Korea is an established and credible nuclear weapons state. Beyond simple plutonium-based first- or even second-generation fission devices, Pyongyang has progressed its weapons designs to include boosted fission devices and may have approached a thermonuclear-weapon status. If it has not yet arrived at the last destination, North Korea is certainly knocking on that door, based on its stated determination to secure the same levels of nuclear weapons capability as that held by the major nuclear weapons states. All concerned must now acknowledge that Pyongyang’s ability to generate ever larger volumes of both plutonium and highly enriched uranium, plus other critical materials required for more sophisticated weapons designs, elevates the North Korean strategic weapons threat to the level of weapons possessed by the world’s established nuclear weapons states.

Rising from a one-shot bomb builder to a program capable of designing, testing, and deploying multiple types of weapons suggests that the North Korean nuclear threat will be with us all for a long time. The otherwise impoverished nation’s programs in ballistic missile delivery systems, incredibly ambitious in their own right, have provided Pyongyang with the ability to credibly target not only South Korea but Japan as well—a traditional enemy it deems to be deserving of a nuclear strike.

North Korean nuclear weapons atop deployed ballistic missiles can target U.S. bases in Japan as well as Guam and Hawaii, which together unpin the United States’ entire political-military strategy in the western Pacific. Such forward basing of U.S. forces is essential to plan for and execute contingencies relating to the growing confrontation with China. By holding these bases at risk, the North Korean regime creates deeper dilemmas and complicates U.S. planning, undermining our ability to properly address the China problem. More recently, North Korea has demonstrated the ability, albeit on a limited basis, to build and launch ballistic missiles with an intercontinental reach, threatening the west coast of the United States.


Irrespective of how the relationship between the United States and the Republic of Korea (ROK) plays out, Japan will look across its western waters and see one of three possible “new Koreas.” In the first scenario, South Korea would continue as it is—that is, as a democracy that ostensibly controls its own territory but has exchanged the U.S. alliance for a position of permanent subordination as a nation to North Korea. Pyongyang would use its nuclear trump card to compel its younger brother to do as it wishes. Even in this best-case new Korea scenario, North Korea would be able to find common ground with the South, politically and emotionally, in viewing Japan as a hostile entity.

A second, but much less likely, scenario would see a South Korea that is still politically independent of North Korea but now free of the strictures previously imposed by the U.S. alliance. This scenario would likely lead to Seoul electing to develop its own nuclear weapons capability. In Japan, such an outcome would be seen as an absolute disaster—two Koreas, each with nuclear weapons, competing to see which nation could find the most creative paths to intimidate their traditional enemy. The ability of the United States to constrain this eventuality, absent the enforcement mechanisms of the U.S.-ROK alliance, would be minimal.

A third scenario, also unlikely in the near term but more probable in the long run, is a unified or “confederated” Korea in which the two countries forge themselves into a single national entity. This scenario would involve a rush to achieve a peace agreement—sometimes hyped as an “end of hostilities” joint declaration—that would promote and allow a limited integration across the full peninsula. A variation on this same worst-case scenario could involve a North Korean collapse due to any number of calamities. These might include a leadership struggle, with South Korea inserting itself to take a heavier hand in the North. Serious Japanese or American planners with exposure to the Korean mindset should assume that a collapsed or fractured North Korea would translate into a nuclear-capable new South Korea.

In several variations of these posited new Korea scenarios, the full integration of the military forces of both countries, at least at the command level, would be inevitable. Such a concession and commitment by the South would be a central goal and a demand of the North.

A corollary reality that may need to be bluntly stated is that Japan does not regard the U.S.-ROK security relationship, at least in its current form, as viable in either the middle or longer term. Even a situation where the United States departs South Korea in a phased step-away, with a sequenced drawdown of the remaining U.S. conventional forces stationed there, would portend the end of that alliance and the removal of the buffer that the U.S. military presence on the peninsula has offered to Japan. As a single catalytic event, the evaporation of the U.S.-ROK security relationship brings immediate consequences to Japan and in and of itself gives cause for a fundamental reconsideration of Japan’s exposure to evolved threats.


The other critical U.S. security ally in East Asia—namely Japan—increasingly shares the U.S. perception of the nuclear threat from North Korea. It does so in several ways that are more extreme and more immediate than its American partner, for obvious reasons of distance, history, and culture. The North Korean ballistic missile threat to Japan, as well as to U.S. bases there, is better defined and more credible than any similar threat to the U.S. homeland. The quality and variety of missiles targeting Japan, the inherent vulnerability of Japanese cities and critical infrastructure, and Japan’s likely inability to defeat fleets of incoming North Korean warheads have combined to dominate Japanese national security planning. Here the North Korean threat is neither abstract nor hypothetical.

Japan must now plan for the strong possibility of a unified Korea that combines the nuclear capabilities of the North and the economic strength of the South. For Japan, this scenario would represent a deadly combination of capability and hostile intent. An unfortunate given is that any unification or confederation between the two current Korean states likely would embrace a shared antipathy toward Japan as a key element of its bonding mantra.

All versions of the new Korea reality would see the United States having departed the South Korean security scene, ending the U.S.-ROK alliance. With that no-fault divorce, the United States would have withdrawn from South Korea the “assured deterrence” previously provided by the U.S. nuclear umbrella. North Korea, based on its political position there and the physical presence of its military capabilities, would have replaced the United States as the nuclear guarantor for the entire peninsula, postured to strike at all enemies (real or imagined). The United States, desiring to maintain a forward posture in East Asia, would opt for a broad strengthening of its commitment to and military relationship with Japan.

This brings us to the ultimate national security decision that now pends for the United States and its bilateral alliance partner. The U.S.-Japan alliance cannot remain as it stands in 2020. The positive attitudes on the part of both governments, accompanied by incremental improvements in Japan’s national security structure and force posture and better coordination with the United States, have worked well up to this point. But Japan now faces a new reality. The core of that awakening is that the U.S. nuclear guarantee must become more credible, more tangible, and much more certain across a range of response scenarios than has been the case in the past.

Failing to reach an acceptable solution within the context of the current alliance, Tokyo and Washington may be forced to examine other options, including a nuclear Japan based on a sovereign deterrence posture linked to that of the United States. Indeed, the Japanese leadership may judge that it must take this course to secure the country. The United States might even elect to shepherd that transition, particularly if it tires of carrying the extended deterrence for others. Indeed, Japan as a declared and credible nuclear weapons state could become a nuclear partner along the lines of the United Kingdom. A U.S. departure from the ROK alliance and the consequent removal of the U.S. nuclear commitment from the Korean Peninsula would make this decision easier. This would be particularly so if Japan asked to open discussions to create such a nuclear partnership based on mutual commitments of extended deterrence that could benefit both parties. In this new Asian nuclear dynamic, anything would be possible.


The only way a U.S. conventional and nuclear deterrent can be made credible for Japan, with assurance of that ultimate deterrence made clear to its potential enemies, is to introduce INF systems to the Japanese mainland. Specifically, members of the next generation of systems now under development by the United States, capable of delivering both conventional and nuclear warheads to targets in the region, must be stationed in Japan.

Ideally these next-generation INF systems would be deployed deep within the context of the alliance, in a dual-key arrangement similar to that which has served NATO. This would require an integration of the command-and-control structure associated with the alliance, with parallel release authorities held by the leaders of both nations. These systems would be assigned both tactical and strategic targets based on advanced joint planning, and options for their use would be well rehearsed and practiced so as to drive home the quality of that joint deployment.

The advantages of such deployed weapons systems, either of a single type or in multiple variations, permanently based on the territory of Japan would be fourfold. First, such a capability would firm up the credibility of the alliance, and specifically the credibility of the U.S. commitment to protect Japan and the U.S. force structure based in the country. Concurrent with the decision to deploy INF-class weapons, the conventional U.S. force structure, as well as the Japanese companion structure, would be expanded to defend the INF systems.

Second, the stationing of INF systems in Japan would send an unambiguous message to hostile regional powers that could not be intentionally misunderstood. In the case of North Korea, and more so in the case of a single “new Korea,” a U.S.-Japan alliance INF force that is dual-capable would erase any doubt in the minds of decision-makers in Pyongyang or Seoul. It would make obvious that a Korean conventional or nuclear attack on Japan would result in nothing less than the destruction of the attacking entity, regardless of what flag it flew. This positioning of a visible deterrent would also checkmate the range and time-to-response disparity that now exists between North Korea and Japan, given Japan’s current reliance on the less visible (and hence less credible) U.S. extended deterrence posture.

Third, a deeply integrated alliance commitment to deploy and operate nuclear-capable INF systems in Japan will, for the life of that deployment, dissuade and deter Japan from going its own way to build an out-of-alliance sovereign nuclear force. Japan today is capable and increasingly inclined to explore this option. A shared-key INF system would fill this requirement for absolute certainty. This would be particularly so if it were well laced together at the national leadership level based on a sophisticated real-time decision-making matrix (including release authority for weapons use).

Fourth, the existence of such an alliance-based INF presence in Japan likely would encourage a regional if not global approach to limit and contain INF-class systems. That is, the regional INF issue would be addressed as part of an international process to create new treaty and enforcement mechanisms that could replace the recently abandoned INF treaty. The latter became useless because the U.S. government was compelled to acknowledge blatant Russian cheating extending back over a decade—the boldness of which promised that there would be even more duplicity on the Russian side if the treaty had been extended.

Finally, another INF scenario for Japan could be the same alliance-centric dual-key control mechanism deployed aboard jointly crewed ballistic missile submarines. This system would be jointly funded, jointly owned, and operated by combined crews detailed for service through a program staffed by both navies. By system definition and classification, the onboard INF systems would be regional strike weapons and include both conventional and nuclear variants. This would permit the operation of the INF systems to occur offshore but be based in both Japan and U.S. territory (Guam), thus creating a capability that would be more survivable and even more credible than the land-based option.


What must be done to address the North Korean nuclear threat in the new East Asian security order? All parties confront a situation that has been created by a North Korean weapons program that will become ever more threatening with time, in company with an agenda that encourages its use as a tool to gain what the Kim regime aspires to achieve. Some of the options discussed above represent necessary adjustments and deterrents that will buy time and a measure of peace, but all fail as an ultimate solution.

We have reached the point where North Korea cannot be disarmed peacefully or convinced to do so through some combination of negotiated threats, concessions, and compromises. Its nuclear weapons have become the core of its existence, central and essential to its survival. This nuclear arsenal is the only remaining instrument by which Pyongyang can achieve its national destiny—the subjugation and absorption of the South. This leaves the United States and its allies with a reduced set of options. But there are always other options out there.

The deployment of INF systems to Japan is one option, but alternative courses of action also exist. It is time for the U.S.-Japan alliance to explore the full range of possible solutions, and to do so in a comprehensive and decisive manner. This process cannot be further delayed. It must begin today.

Richard Lawless is a Founder and Principal of NMV International. He served the U.S. government for over twenty years, including as Deputy Under Secretary of Defense for Asian and Pacific Security Affairs. In this capacity, he was responsible for formulating U.S. security and defense policy in the Asia-Pacific. He was also a career operations officer of the CIA from 1972 to 1987, where he specialized in nuclear proliferation issues. His forthcoming book Hunting Nukes: A Fifty-Year Pursuit of Atom Bomb Builders and Mischief Makers is currently undergoing Agency review prior to publication.

This commentary is adapted from an article originally published in Japanese in the December 2020 issue of Wedge magazine. An English translation of the full article is available at

U.S. Army photos by Sgt. John L. Carkeet IV, U.S. Army Japan