Before Robert McNamara became US secretary of defense, he belonged to a generation of analysts who attempted to understand warfare through the lens of measurable flows. During WWII, McNamara examined bomber operations by using parameters such as aircraft utilization, losses, mission rates, maintenance requirements, and operational efficiency while serving in the US Army Air Forces’ Office of Statistical Control.
The enduring lesson that can be learned from him is not that looking at spreadsheets alone would ensure victory in war: experience from the Vietnam War illustrates the danger of confusing strategic success with measurable activities. Rather, McNamara’s earlier works offer some useful principles in an era of industrialized drone warfare: nominal inventories have less importance than the ability to transform equipment, manpower, and industrial capacity into sustained battlefield effects.
Such a distinction should increasingly shape the defense planning of both Japan and South Korea. The two countries are confronting adversaries in the region that could combine greater quantities of missiles, artillery forces, and unmanned systems. The introduction of affordable and expendable platforms indicates that attrition, sortie generation, replacement, and adaptation—alongside traditional measures of force structure—have become important elements in evaluating defense capabilities.
Calculate Sorties, Not Drones
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Consider two militaries. At first glance, it would offer an impression that country X enjoys overwhelming superiority over country Y if the former has 100,000 drones, while the latter only possesses 40,000. But if country X can only manufacture 5,000 drones per month for replacements while country Y could churn out 20,000 drones within the same timeframe—and if electronic warfare reduces country X’s successful engagement rate to 10 percent, whereas country Y achieves 30 percent—the actual advantages would look different.
When it comes to drone warfare, a similar equation to that applied to strategic bombers during the 1940s is required. Here, criteria like daily sortie rates and penetration of enemy defenses should be included. In modern warfare, another important variable—namely adaptation time—needs to be added. If the opponent introduces a new electronic jamming technology, for example, war planners should estimate how many days pass before modified communication software or hardware arrives at the frontline units. A military that could upgrade drones every two weeks could reap better outcomes compared to an opponent that upgrades drones every six months, despite the latter’s edge in technology at the initial phase of the war.
South Korea and the Economies of Saturation
South Korea provides an obvious test case. The South Korean government has recently announced that it would acquire roughly 60,000 unmanned systems by 2029. It also plans to acquire more than 20,000 low-cost expendable systems by 2030 while the number of personnel trained to operate drones is planned to be increased substantially. Nonetheless, the likelihood of North Korea pairing ballistic missiles, artillery, and unmanned systems implies that South Korea should seriously think about how to inexpensively defend against repeated mixed attacks, and not simply how many drones Seoul could operate in the near future.
Suppose North Korea launches affordable drones and decoys alongside more destructive ballistic and cruise missiles. Although intercepting 96% of the incoming targets could undoubtedly be an impressive tactical outcome—this is the success ratio of the South Korean Cheongung-II missiles demonstrated in this year’s Iran war—this exchange ratio could remain advantageous to Pyongyang if Seoul frequently consumes its high-end interceptors to respond to low-cost threats. Therefore, South Korea should calculate the cost per single engagement and overall inventories aside from the interception ratio.
This requires a much clearer division of labor within South Korean air defense. Expensive interceptors such as Patriot, KM-SAM, and L-SAM should be preserved for threats that specifically require the use of these weapons systems, while relatively inexpensive means—guns, electronic warfare, lasers, and interceptor drones—should address low-tier threats. Instead of examining whether South Korea could defend against a single large-scale salvo attack, the test should be focused on whether Seoul could defeat multiple rounds of salvo attacks without depleting high-end interceptors needed against the most perilous missiles.
The value of an inventory of tens of thousands of drones would remain limited if wartime losses could not be replenished due to the lack of motors, batteries, optics, and communication components interrupting continuous drone production. Naturally, weapons acquisition should inevitably accompany the estimation of realistic wartime consumption and an evaluation of the industrial capacity required to sustain it.
Japan and the Geography of Unmanned Warfare
Despite the different operational geographical environment, Japan has similar arithmetic issues. Japan’s new Synchronized, Hybrid, Integrated and Enhanced Littoral Defense (SHIELD) concept envisions large numbers of UAVs, unmanned surface vehicles (USVs), and unmanned underwater vehicles (UUVs) operated together with conventional forces. This approach is particularly relevant across the Nansei Islands, where Japan needs to monitor vast maritime and aerial battlespaces and potentially defend against much larger Chinese forces.
Tokyo should thus measure surveillance and operational coverage-hours, and not simply the quantity of acquired platforms. For each island node, defense planners should calculate how many reconnaissance sorties are needed to maintain sustained surveillance, the number of unmanned systems that could be lost in a week, and how replacements could rapidly reach the operational theater. Moreover, it should be examined whether dispersed launch sites, communications nodes, and sensors could continuously function even after missile attacks on major bases.
A particularly useful metric would be restoration time. If 30 percent of surveillance and communications capacity near Miyakojima and Ishigaki loses its function, Japan should be aware of how much of that damaged capacity could be restored within 24 hours, 72 hours, and one week, respectively. Such calculations would transform an abstract policy objective of ‘resilience’ into measurable operational requirements.
Japan and South Korea Should Count Together
The most important application of McNamara’s approach should occur in the field of Japan-South Korea cooperation. Where appropriate, Tokyo and Seoul should establish a classified 30/60/90-Day Munitions and Unmanned Systems Dashboard, in coordination with the United States. Its purpose would be narrow, yet it could bring substantial benefits—identifying precisely when their key capabilities would face constraints in a protracted dispute in Northeast Asia.
The dashboard should include air and missile defense interceptors, long-range precision-guided munitions (PGMs), conventional ammunition, expendable UAVs, counter-unmanned aircraft systems (C-UAS), and critical components. War planners could start by examining the existing weapons inventories, apply expected wartime expenditure and attrition rates, factor in realistic production and maintenance capacity, and calculate the resulting stockpiles after 30, 60, and 90 days. Such work could reveal bottlenecks—including rocket motors, explosives, batteries, semiconductors, or a lack of production capacity—that the peacetime figures conceal.
This could also turn defense industrial cooperation between Japan and South Korea into a more concrete form. While Japan has strengths in the fields of advanced materials, sensors, electronic equipment, robot engineering, and maritime technologies, South Korea has considerable advantages when it comes to mass production, batteries, missiles, artillery ammunition, and unmanned systems. Tokyo and Seoul should identify specific cases in which Japan’s production capacity could remove South Korea’s bottlenecks—and vice versa—while collectively reducing dependence on vulnerable external supply chains.
Recalculating the Northeast Asian Balance
Such analysis is increasingly necessary since China, Russia, and North Korea present different but complementary problems. China has the region’s largest industrial foundation and vast civilian drone and electronics industries that could potentially support military mobilization. Russia has accumulated comprehensive experience in rapidly modifying drones, electronic warfare systems, and frontline tactics throughout the Russo-Ukrainian War. Meanwhile, North Korea has gained combat experience and deepened its military and industrial cooperation with Moscow.
This is where cooperation with the United States becomes particularly important. Instead of relying on force comparisons based upon the traditional static bean count, Washington, Tokyo, and Seoul should compare expected consumption, production, maintenance, and adaptation rates against plausible adversary rates. A coalition that possesses advanced technologies but needs two years to replace weapons that are depleted within a couple of months could confront a fundamentally different military balance from that suggested by the peacetime order of battle.
McNamara’s Final Warning
There is nevertheless a reason why McNamara should be considered both a teacher and a warning. During the Vietnam War, he demonstrated how quantifiable metrics such as body counts could generate an illusion—that the situation was controllable—especially when they were separated from political objectives and frontline reality.
McNamara’s most useful lesson in the drone age is, therefore, narrow but powerful: military power heavily depends on what could be repeatedly created during wartime, rather than what a country owns at the beginning of a conflict. In that sense, the decisive statistical metric in Northeast Asia may not be how many rounds of missiles or drones Japan and South Korea have when a regional contingency erupts. It may be how many effective weapons are churned out, replaced, and upgraded after the hundred-day mark.
