Lessons for US Military Strategy from the Human Immune System

War theory of the immune system — shaped over millions of years with microbes and viruses — could inform military strategy.

It is time to give immunology a seat at the security affairs table. The marriage of such disparate fields seems ludicrous on its face. However, humanity should not ignore that its immune system has already fought and won trillions of conflicts with microscopic nation-states, such as viruses, bacteria, fungi, and parasites. Moreover, given its success, the immune system may inform thinking on great power politics at a macro level.

That is what entered my mind when I took my first international affairs course at the age of 46, a short sabbatical to extend my training away from life sciences. Importantly, I learned to overuse the word “hegemony,” which seems like a rite of passage in the international affairs world and a ticket to respectability among my political science peers. The word was never used during my PhD studies in immunology, although it could have been.

Here’s why.

The human body has a clear grand strategy. It has key interests (i.e., security and prosperity), external and internal threats (i.e., infectious agents and cancer), a military strategy (in the form of the immune system), and forces to achieve its interests (i.e., immune response). Therefore, understanding the immune system is essential to illustrating how the human body executes this grand strategy, especially regarding military actions.


Realism is defined by five assumptions: the international system is anarchic, great powers possess offensive military capability, states cannot be certain about other states’ intentions, survival is the primary goal of great powers, and great powers are rational actors. Do these assumptions define the interaction of microbiota with the human immune system?

The human body’s immune system is anarchic. The human international system, composed of hundreds of trillions of cells (human cells and microbial cells), has no central governing authority that assigns position, role, status, or survival strategy. Microbial communities change in our body from birth until death; it is dynamic. These microbial communities often wage war against each other and the human body.

In today’s political and military climate, therefore, the immune system model is timely: strengthen the homeland, limit wars that consume valuable resources, and largely fight from a graded, standoff position.

Infectious agents and the immune system possess tremendous molecular offensive capability. The complex field of immunology highlights the body’s offensive arsenal.  Microbes and viruses also have their own conventional weapons (i.e., toxins, invasion factors, cytokine decoys, etc.) and nuclear weapons (such as the ability to destroy the entire immune system by eliciting a global inflammatory response, the way Ebola/Lassa fever does). In order to emphasize the peril of certain pathogens going to war with the immune system, humans categorize the most dangerous pathogens into what are called “select agents.” These particular microbes and viruses’ offensive capabilities are acutely dangerous. Thus, their development, production, or storage has been outlawed since the Biological Weapons Convention in 1972.

It is true that states cannot be certain about other states’ intentions. Similarly, the immune system is never sure what pathogens or microbiota it will encounter during its lifetime. Therefore it casts a wide net during its development, producing >30,000,000 different variations of T cells that could recognize an incoming foreign nation-state. COVID-19 is an illustrative example of how the immune system may or may not be ready for this pathogen. Some strains of viruses are relatively benign, some are deadly, and these strains evolve. The immune system is forced to constantly adapt, and sometimes it is unprepared.

Survival is the primary goal of great powers. Richard Dawkins, the author of “The Selfish Gene,” stated, “they [genes] march on. That is their business. They are the replicators, and we are their survival machines. When we have served our purpose, we are cast aside. But genes are denizens of geological time: genes are forever.” Simply stated, any biological system that contains genes is focused on survival and passing those genes to the next generation. This is true for all life.

Great powers are considered to be rational actors. Microbiota and human cells, especially the immune system, constantly adapt to changing conditions, thereby making complex choices that are communicated to the rest of the community. External stimuli are translated into signals that allow the system to evolve (this is traditionally termed “quorum sensing” for bacteria). At a biochemical level, the rationality of both microbial and human cells is evident and often stunning in its complexity and elegance.

At a fundamental level, realism and the human immune system operate under the same assumptions.


There are three main lessons for US military strategy. The first has to do with the duration of the fight. As Sun Tzu said in The Art of War: “There is no instance of a country having benefited from prolonged warfare.”

How the immune response is managed from a resource allocation perspective is well studied. The nutritional responses during a generalized infection include alterations in protein synthesis and degradation rates, fatty acid and carbohydrate metabolism, and alterations in the metabolic processing of individual amino acids, electrolytes, minerals, trace elements, and vitamins. Translated into grand strategy, this would mean that if a world power is perpetually involved in international conflicts, it will likely be unable to strengthen itself to an optimal position, which may be important when a more serious challenge arises. Based on the current international climate, John Mearsheimer astutely concludes, “we should see evidence of each side’s pursuing a bait-and-bleed strategy when there is an opportunity to lure the other side into a costly and foolish war.” The immune system must make this decision daily, and it chooses to maintain the health of the human body by limiting foolish wars.

Second, a common argument against retrenchment/offshore balancing is that if a serious war erupts, it will be too late to mobilize military resources to confront the threat. The immune system would say that fighting a war with a ramp-up delay is the optimal way to confront a foreign nation-state, at least from an evolutionary perspective.

When a threat is first encountered, the immune system appears to be relatively unprepared. The reality is that the immune system always has innate immunity in place that enables the detection of the pathogen entering the system; this would be the equivalent of a myriad of detection systems and first-line protections employed by world governments. Once the threat attempts to expand power (by migrating and replicating), the body begins to reallocate resources to confront the threat through various methods, but mainly expanding weapons that it has held in reserve (B and T cells).

The response is never starting from zero, it is starting from a place of latent power. Thus, the immune response — although delayed — can eventually overwhelm and clear the threat. The response to World War II is a good analogy. The United States had a strong homeland, and military forces were deployed with the homeland (picture Pearl Harbor). An attack occurred, and the system responded by ramping up, extinguishing the threat over time (the Pacific theater campaign of World War II), and then ramping back down. Yes, the confrontation comes at a terrible cost, like when an infection in the body takes weeks, sometimes months, to clear, with a generous amount of pain and suffering. However, the result is the return of the human body to the biological hegemon that it has evolved to be. The key is that the immune system requires rest (or low periods of activity) to maintain its hegemony.

Finally, a major immune system strategy is to practice “over the horizon” attacks via lymph nodes and the lymphatic system. The fluid that leaks for blood vessels in peripheral tissues collects, and is channeled through the lymphatic system, and returned to the blood supply. In the process of returning to the blood supply, lymph is filtered through lymph nodes where surveillance for foreign particles occurs. Suppose foreign pathogens have migrated deep into lymph nodes. In that case, it means that first layer “deterrence” defenses have been breached (innate immunity), and now it is time for a more robust, “targeted” response (adaptive immunity). Cellular weapons enter the bloodstream and migrate back to the site of the infection to engage the enemy (i.e., over the horizon).

It is important to note that lymph nodes are very much in a standoff position. They did not evolve to be positioned at the direct interface between human cells and foreign nation-states — whether they are harmful or benign. Lymph nodes are in the interior of the body, entrenched in human tissue. Pathogens, or cells containing pathogens, must migrate to them first. Then lymph nodes activate once a specific threat has been detected within the sovereignty of the human body. The sledgehammer of adaptive immunity is then activated. In today’s political and military climate, therefore, the immune system model is timely: strengthen the homeland, limit wars that consume valuable resources, and largely fight from a graded, standoff position.


According to the Costs of War Project, the 20-year Global War on Terror has cost the United States at least $8 billion and >900,000 lives. This includes post-9/11 wars in Iraq, Afghanistan, and others. Americans have seen chronic military engagement, spending, and inflammation (both social and political). Metaphorically speaking, the US “immune system” went from targeting a specific pathogen (al Qaeda and Osama Bin Laden) in 2001 to spreading out to more nebulous targets such as the war in Iraq (2003–2010), the war in Afghanistan (roughly 2001–2012), followed by a decade of withdrawal of US military and government resources during a time that enemy-initiated attacks remained extremely high (>25,000 attacks per year). Our military trajectory in Afghanistan was eerily similar to an unsuccessful attempt by the immune system to overcome tuberculosis: first acute illness, followed by chronic disease, leading to eventual system (strategic) failure. What might immunology suggest about the future Global War on Terror?

The vagueness of the “what” of the Global War on Terror is a lesson on blurring the lines between self and non-self. How does the US military fight an abstract idea? Who represents terror?

The immune system’s power to wage war rests on a key principle: discrimination of self from non-self. It utilizes a presentation system on the surface of almost all human cells to display molecular markers that either communicate “it’s me, all is well” or “this is foreign, attack!” It is extremely specific for the target it is attacking, whether it be a virus, bacteria, or parasite — each of which would elicit a tailored, unique response by immune cells. A defined target is essential to immune system success. The vagueness of the “what” of the Global War on Terror is a lesson on blurring the lines between self and non-self. How does the US military fight an abstract idea? Who represents terror? If terror is universal, then can we fight everyone, including ourselves? This immunology lens may indeed give a fresh perspective to the Posse Comitatus Act — a law to prevent the military from causing an “autoimmune disorder” by interfering in civilian affairs.

Another aspect of immunity that could inform future military strategy is speed, i.e., not solely the speed of the attack, but rather the attack coupled with the speed of the draw down. In John Hersey’s words, a correspondent who accompanied soldiers on the Battle of Guadalcanal, soldiers fought “to get the damn thing over and go home.” Attack and return — a strategy endorsed by the immune system, resulting in the system’s health. All of us have been sick and know the value of a quick recovery after a brutal illness. The same principle is advocated within offshore balancing: “once the threat had been dealt with, US military forces could go back over the horizon and not stay behind to meddle in local politics.” Remember, the immune system isn’t supposed to meddle. When it does, the result is erosion of health and chronic pain.

The power to shape our biological future is a product of a winning approach encoded in our DNA and passed on to subsequent generations. War theory of the immune system — shaped over millions of years with microbes and viruses — could inform military strategy. A method for introducing these concepts establishes a melting pot for new ideas to emerge, such as an AI predictive tool (with inputs modeled from the body’s defense system) to better forecast war outcomes. The hypothesis is that the overlap of immunology and US military strategy would result in a creation equal to dipping fries into ice cream: deplorable to explorable?

Matt Lyman is a Research Scientist in the Biosciences Division at Lawrence Livermore National Laboratory. The views expressed here are his personal views and should not be attributed to his employer or its sponsors.