Six Lessons from Ukraine for Japanese Defense Planners

Japan visit

Japanese leaders have already begun internalizing key lessons from Ukraine. As shown in a triad of strategic documents released last December, Tokyo is ramping up spending on munition stocks, maintenance, and base hardening and readiness, as well as making new investments across all domains. But despite this, Japanese officials are silent on whether they are preparing for a short conflict or a long one. This matters because, as the Ukrainian war demonstrates, a protracted struggle could require different plans from the ones Japan is possibly making.

Any conflict involving China and the United States is unlikely to be a short one. For Japan to participate effectively in any East China Sea conflict — even in its own defense — Japanese forces should take six key lessons from the current fight in Ukraine: prepare for a protracted conflict; ensure an adequate logistics posture; be ready for active combat; assist the broader fight; use unmanned capabilities; and sustain the will to fight. Addressing these issues can help Japan — and the alliance — become better prepared to rapidly respond in support of U.S. operational timelines.



Preparing for a protracted conflict

The first step in preparing for a protracted conflict involves stockpiling and prepositioning critical materiel like fuel, parts, equipment, supplies, and medical supplies close to the units that will need them. Ukraine’s experience also suggests Japan should place a priority on ensuring equipment and units are in high states of readiness.

Arguably the most critical lesson is to ensure adequate stockpiles of munitions are available where fire units are located. Like pre-war Russia, China will start any war with a vastly numerically superior aircraft and ship inventory compared to what the allies currently have in theater. This, along with their large inventory of missiles, will hold the entire Japanese archipelago at risk. In addition to putting a premium on both passive and active Japanese base defenses, this reality also highlights the importance of Japan maintaining its industrial base and robust munition stockpiles. To be fair, Japan identified the importance of increasing munition stockpiles in its 2022 National Defense Strategy, but it is unknown what the Ministry of Defense and Self-Defense Forces have assessed to be sufficient. This brings us back to what type of conflict the Ministry of Defense is preparing for.

Prepositioning and stockpiling for a short-burst conflict versus a long-term protracted conflict like Ukraine involves very different levels of effort. The U.S. Army, for example, has confronted the issue of how to refill dwindling weapon stockpiles that have been diverted to provide support to the Ukrainian military. The war in Ukraine is one in which the U.S. is providing indirect support. Stockpiles would go down much faster if the U.S. were directly involved in the fighting. For Japan, part of the government’s current objective is to backfill stocks of critical munitions during peacetime. Unknown is what sort of deals the Ministry of Defense has made with weapon suppliers for increased production in a conflict. Given the small number of suppliers, does Japan have the ability to increase capacity in wartime? Also unknown is whether Japan is working with U.S. suppliers to deconflict its orders with those of the U.S.

Ensuring an adequate logistics posture 

This raises the issue of how Japan intends to get critical supplies where they are needed once its stockpiles and materiel start to run low. One deficit in Russian operations was logistics, due potentially to poor training and, more observably, to poor planning. As U.S. Army Secretary Christine Wormuth notes: “The Russian military has struggled with moving equipment around the battlefield…[displaying] a notable and somewhat surprising deficiency in this area.” Seth Jones provides further elaboration, arguing that without access to rail transport and with roads clogged with Russian vehicles, “Russian ground forces failed to move fuel, munitions, spare parts, and other matériel quickly and efficiently to forward-deployed units,” making supply lines unable to keep up with long combat pushes. The result of these failures in logistics has been borne out on the battlefield where supply lines are bogged down, leading to floundering offensives and loss of land when faced with Ukrainian counter-offenses.

Any conflict involving Japan will immediately involve a logistics trail spread across multiple islands separated by hundreds, sometimes thousands, of miles of water. Because it is fighting from its territory, the Self-Defense Force will always have bases, stockpiles, and supplies somewhere nearby — but that “somewhere” may be separated by mountains or large swaths of ocean. In peacetime, Japan tends to rely on commercial assets to supplement the Self-Defense Force in moving supplies and equipment around. This creates significant vulnerabilities and potential legal issues in the run-up to a crisis, not to mention during an actual conflict.

For a contingency, ensuring the Self-Defense Force has the capacity and capabilities to transport munitions, fuel, and supplies quickly to where it needs to go will be critical to remaining in any fight. I have written about what I view as Japan’s paucity of sealift and airlift previously. Because there is no significant focus on lift capabilities in the 2022 documents (although there is some mention of small watercraft and private capabilities like civilian ferries), I still believe there is a danger. The Self-Defense Forces may confront limitations in quickly moving supplies and personnel throughout the archipelago in a sustained manner where significant attrition is expected to take place. While civilian options are always possibilities to make up for shortfalls, their use in a conflict will be highly constrained.

Preparing to fight in active combat 

While it is important to focus on ways to keep the Self-Defense Forces in the fight, an often-unasked question is whether they are prepared for active combat. One of the surprising aspects of the war in Ukraine has been the incompetence of the Russian military. Prior to the war, articles argued that Putin’s military was modern and competent, leading to the expectation that Russian military superiority would make quick work of Ukraine. Instead, whether it be combined arms operationsfuel and logistics supplyplanning and combat readiness, or command and control, the Russian military has made critical mistakes, compounded by corruption on a massive scale.

It is not uncommon to view the People’s Liberation Army as a similarly daunting military giant. Yet, its military competence is untested, with the last conflict it fought — and lost — coming in 1979 against Vietnam. Nevertheless, even that decades-old operational failure by the People’s Liberation Army amounts to more combat experience than the Self-Defense Forces have had. While Japanese forces have decades of experience in responding to disasters, experience related to active combat is limited to exercises and training. The Self-Defense Forces are said to not routinely conduct realistic exercises or practice realistic training. Some exercises that would be necessary for high-end combat readiness, like missile training, cannot even be performed in Japan because of domestic political considerations.

Recent joint statements have identified “realistic training and exercises” as an area of focus for the alliance. It is unknown to what extent Ukraine’s battlefield successes have influenced efforts to improve Self-Defense Force tactical combat skills and readiness levels. For example, is Japan watching the war and looking at ways to improve its combined arms operations as a joint force? The U.S. Army, for its part, has been talking about the importance of joint training exercises that offer experience in large-scale maneuvers. Given the Self-Defense Forces’ sophisticated equipment and plans to procure more in the years ahead, the more Japan can improve high-quality, realistic training to build capacity and train junior leaders and non-commissioned officers to make battlefield decisions and seize the initiative, the more ready it can be to put its sophisticated equipment to the most effective use against a numerically superior adversary. The planned establishment of the permanent joint headquarters also suggests a greater seriousness about jointness, which could pay dividends against a much larger Chinese force.



Assisting the broader fight

In addition to being ready to fight, a more fundamental question for Japanese political leadership is what role it sees itself playing in a Taiwan contingency. I have written extensively about how Japan’s legal framework delineates what it can and cannot do in different scenarios. In this context, planners should begin thinking creatively about all the different ways Japan could assist Taiwan in maintaining its ability to fight.

One of the most critical forms of cooperation that has benefited Ukraine is the West’s resupply of arms and munitions. While this has slowed as the war drags on, at one point the U.S. and NATO supplied Ukraine with more than 17,000 anti-tank weapons in less than a week. Japan provided Ukraine with supplies, but not combat materiel. If maintaining a viable government in Taipei is a critical interest for Tokyo, Japan would presumably also be willing to support Taiwan in a similar manner. Would Japan resupply Taiwan with weapons and munitions in an active contingency? It is impossible to know if a future Japanese prime minister would find that too provocative. If it were, perhaps non-kinetic support like Self-Defense Force C-130s and C-2s supporting airdrops of non-combat materiel into Taiwan would be more realistic. And if flights near or over Taiwan prove politically or operationally difficult in a contested environment, Japanese forces should at least be able to use some of their KC-46 aerial tankers to help sustain refueling efforts of coalition forces flying from Guam or Alaska. This kind of non-kinetic, rear-area support over international waters should prove the least politically and operationally difficult.

Regarding combat operations, a fight for Taiwan will involve multiple missions. If Tokyo does enter the fight, the big question will be whether it limits its support strictly to Japan’s defense or if it will expand its support to defending U.S. forces in and around Japan. If it takes the latter approach, consistent with the stated intent of its 2014 reinterpretation of Article 9 to allow collective self-defense, the question then turns to what types of missions it would engage in. The 2015 mutual defense guidelines provided an answer, as that document offers a general roadmap of the expected roles and missions each ally will participate in. But with Japan having taken a more proactive stance, the expected roles and missions for the Self-Defense Forces will depend wholly on who occupies the Kantei at that time.

Can the United States only count on critical non-combat, rear-area support tasks such as intelligence, surveillance and reconnaissance, refueling, maintenance, and search and rescue? What about air or maritime operations that involve kinetic activities outside of Japanese waters and airspace, including combat search and rescue, in support of allied forces? What about defending the flow of critical U.S. materiel into the theater and onward to the forward point of need, even if that includes Taiwan itself? While the United States would no doubt want Japan to provide a robust response, it should not come at the expense of the Self-Defense Forces fulfilling their core responsibility of defending Japan.

Arguably one of the biggest unknowns is how Japan intends to utilize its long-range precision fires. Most Western security analysts and defense planners consider such capabilities to be offensive in nature, but the debate in Japan has focused on how they can be used for self-defense purposes. Much of this debate has centered on targeting adversary airfields or fixed military facilities. Aside from the fact that these number in the thousands and airfields can be relatively quickly repaired, a broader question is what mission objective such strikes would serve.

Since strikes on airfields alone will do very little to deter further Chinese aggression, an important lesson Self-Defense Force commanders could learn from Ukraine is the need for long-range precision fires to sink ships and destroy supply convoys, hit command posts or command ships, and destroy critical logistical and munition nodes. Should the Self-Defense Forces develop concepts of operations that expand their use to these targets, it will be much more likely to complicate People’s Liberation Army operations. Japan may one day acquire an independent kill chain architecture to employ these fires. For the foreseeable future though, it will remain dependent on U.S. intelligence, surveillance and reconnaissance, targeting, and mission planning for these types of operations, requiring close cooperation with Washington.

Using unmanned capabilities

One of the more interesting lessons to come out of Ukraine concerns not just the pervasive use of unmanned platforms by both sides, but the creative ways in which they have been used. Ukrainians have proven very skillful at creating targeting software and other battlefield innovations that can be readily used by soldiers in the field. All of these have demonstrated the effectiveness of unmanned systems for intelligence, surveillance and reconnaissance, kinetic attacks, and targeting purposes.

In Japan’s 2022 National Defense Strategy, the importance of developing unmanned platforms is listed as a priority. And the successful deployment of U.S. unmanned platforms to Misawa, Yokota, and Kanoya Air Bases is proof Tokyo supports big-platform drone operations from Japan. But questions remain about how Tokyo intends to use unmanned capabilities since it is still very much in the exploratory phase of this technology. For example, prior to Russia’s invasion, most Japanese thinking on unmanned platforms centered on procuring big platforms, like the Global Hawk. But the war in Ukraine suggests that all the important roles in a conflict can be carried out by small and cheap platforms, such as loitering munitions.

For Japanese planners looking to find ways to penetrate China’s anti-access, area-denial bubble, more consideration should be given to smaller “attritable” platforms — cheap, single-use weapons that can be purchased in much greater numbers. Similarly, it would make operational sense for the Self-Defense Forces to train small tactical units with the ability to discretely deploy on the battlefield, even beyond line-of-sight distances. Critically, it is still unknown to what extent Japanese planners are working to update their command-and-control networks to integrate the rapid intelligence these unmanned platforms provide into strike platforms currently being procured.

What does not appear to have gotten as much attention in Japan is the risk Chinese unmanned platforms could pose to Self-Defense Force bases and capabilities. The use of drones in Ukraine has become similar to the use of improvised explosive devices in Iraq and Afghanistan. From a defense perspective, it is unknown what lessons the Self-Defense Forces have learned when it comes to preparing for China’s possible use of large numbers of loitering munitions. For example, in the new strategic documents, there do not appear to be efforts to defend against new, smaller, loitering capabilities that can attack from above. Nor does there appear to be a robust debate on improving counter-drone technology as part of a broader modernization of Japan’s integrated air and missile defense systems.

Sustaining the will to fight

One final lesson from Ukraine may be the hardest to talk about in Japan. In a major conflict, widespread destruction would not necessarily be limited to Self-Defense Force bases. Russia’s attacks on Ukraine have been indiscriminate, targeting civilians and attacking infrastructure that civilians depend on. For Japanese planners, the first question that should be asked is whether its current air and missile defense systems, which largely concentrate around Japanese and U.S. bases, are sufficient for saturation attacks. What about defending large population centers?

The December strategic documents suggest that there is a heightened sense of concern over low stockpiles, for example, but other types of investments are also needed. Possible measures could include robust electronic warfare capabilities to degrade incoming missiles, space-based sensors to detect, track, and target incoming missiles, and some combination of more interceptor capabilities for both ballistic and cruise missiles. These in turn could include the Thermal High Altitude Area Defense system, Aegis Ashore, Indirect Fire Protection Capability, or a more robust anti-cruise missile capability not yet developed. All of these are important means to prevent widespread destruction coming from the sky, which could sap the public’s confidence in any prime minister trying to stay in the fight.

To date, much of the domestic debate in Japan over counterstrike missiles has focused on deterrence by denial. But the consequences of their use do not always appear to be discussed in public debates. If Japan uses these capabilities to strike People’s Liberation Army targets but accidentally hits a non-military target or a target that also houses a strategic asset, China may choose to respond with much greater force, including attacks on civilian infrastructure or population centers. Is Japan ready for this? In a protracted fight in which Japan is being attacked daily, will it become more difficult for a Japanese prime minister to sustain Self-Defense Forces’ participation? Or will the Japanese population become more determined to resist the aggressor in the face of regular loss of life? Even more critically, is there a point or redline at which it will become difficult for a prime minister to allow U.S. forces to continue to prosecute the war from bases in Japan?


Japan is making huge strides to improve its defenses in ways that most analysts thought were not possible even a few years ago. All of that is exceptional. Yet, as the Ukraine conflict has taught us, wars can drag on for a long time. Ukraine benefits from having a committed set of international partners that are not engaged in the war itself. In a Taiwan conflict, by contrast, the United States might well be directly involved. That puts a premium on Japan ensuring that it has the ability to not just withstand the first volley, but months and possibly years of fighting. By drawing lessons from Ukraine, Japanese planners can better prepare for that risk.



Jeffrey W. Hornung is a senior political scientist at the RAND Corporation and an adjunct professor at Georgetown University. 

Image: Department of Defense photo by Erin A. Kirk-Cuomo