Future combat will take place in dense urban areas and likely in megacities, or so we are told. These are the new “truths” that are taking hold in the U.S. military. According to Army Chief of Staff Gen. Mark Milley, who is likely the next chairman of the Joint Chiefs of Staff, “In the future, I can say with very high degrees of confidence, the American Army is probably going to be fighting in urban areas.” Gen. Stephen Townsend, commanding general of the Army’s Training and Doctrine Command, took it a step further: “[W]e’re going to see battle in megacities and there’s little way to avoid it.” For its part, the Marine Corps is beginning a multi-year experiment on enhancing urban operations. A recent solicitation by the Marine Corps Warfighting Laboratory notes: “The experiment provides warfighters the opportunity to assess the operational utility of emerging technologies and engineering innovations … for sensing, speed of decision/action and lethality in dense urban environments.” Finally, Air Force Chief of Staff Gen. David Goldfein stresses that because Milley and Marine Corps Commandant Gen. Robert Neller are emphasizing urban warfare, “we’ve got to focus on urban warfare … Wherever they go, so goes the Air Force. … We go as a joint team.”

The recent urban battles in Grozny, Fallujah, Baghdad, and Mosul are often given as examples of this need to prepare for urban combat, as is the inexorable movement of the earth’s populations to cities, particularly megacities with populations of over 10 million. In the interest of full disclosure, I contributed to this dialogue to some degree when I was director of Gen. Ray Odierno’s Chief of Staff of the Army Strategic Studies Group when it published in 2014 Megacities and the United States Army: Preparing for a Complex and Uncertain Future. I have also authored, with my colleagues at RAND, studies on combat operations in Madrid during the Spanish Civil War, Prague during Russia’s 1968 intervention, Panama City during Operation Just Cause, Mogadishu during the United Nations Operation in Somalia II, Grozny during Russia’s Chechen Wars, Fallujah and Sadr City during U.S. operations in Iraq, and Israel’s operations in Lebanon and Gaza.

David Kilcullen and John Spencer are also important voices in the discussion of future urban operations. Kilcullen, in Out of the Mountains: The Coming Age of the Urban Guerrilla, contends that the “four emerging megatrends of population growth, urbanization, littoralization, and networked connectivity … will affect all aspects of life on the planet in the next 20 to 30 years, not just conflict.” Since these urban areas will be the locus for populations, the military should “be thinking hard and unsentimentally about what to do when we find ourselves in an urban, networked, littoral conflict.” Spencer, a retired Army officer with combat experience in Baghdad, who is now the chair of urban warfare studies at the Modern War Institute at West Point and co-director of the Urban Warfare Project, mainly focuses his attention on a subordinate question: If the U.S. military is convinced that dense urban terrain is where it will fight, what is it doing to educate and train itself for this reality?

I still believe that urban combat poses some of the most difficult challenges a military can face. Nevertheless, as this current urban combat juggernaut picks up momentum, it is time to ask several fundamental questions: Why would you fight in cities? Who will you fight in cities? Which cities are possible combat sites in the future?

“Truths” about Fights in Cities

There are a number of broadly shared views about urban combat that are reflected in the literature and doctrine. First, as Carl von Clausewitz noted, in wars between states, cities — particularly capitals — are often considered centers of gravity, as was the case with Carthage, Rome, Paris, Berlin, Grozny, and Baghdad in wars of the past. Second, increasingly, there are those who believe mega-cities are central to the future security environment, a point I will discuss later. Third, there is consensus that an enemy defending in the city has significant advantages, and that dense urban terrain, urban canyons, and underground warfare are likely future challenges.

Indeed, this is why past U.S. doctrinal manuals emphasized avoiding urban areas if possible because many past battles — for example, Aachen, Metz, and Manila in World War II, Seoul during the Korean War, and Hue during the Vietnam War — demonstrated the reality that urban combat can be extremely costly both to one’s combatants and the civilians in the contested city. In these fights, U.S. forces adapted and prevailed in what were often one-offs in the context of major offensive operations in a larger war. Iraq, particularly the battle for Baghdad, demonstrated urban operations can be protracted with cities as the principal environment for operations, and, as Clausewitz noted, the center of gravity.

An Old Debate

The inevitability of global urbanization is not a new topic. For over two decades the National Intelligence Council’s Global Trends reports have assessed the implications of global urbanization and megacities and the challenges they could pose. The U.S. military has also had an on again, off again infatuation with the implications of urbanization. The Navy’s 1992 From the Sea: Preparing The Naval Service For The 21st Century, promulgated to structure the Navy for relevance after the demise of the Soviet Union, was a “fundamental shift away from open-ocean warfighting on the sea toward joint operations conducted from the sea.” The 1997 Forward from the Sea… The Navy’s Operational Concept focused on the littorals, stressing that “Seventy-five percent of the Earth’s population and a similar proportion of national capitals and major commercial centers lie in the littorals. These are the places where American influence and power have the greatest impact and are needed most often.” The Marine Corp’s emphasis also shifted to urban fights, most memorably with Marine Corps Commandant Gen. Charles Krulak’s elaboration of his three-block war concept in 1999. Krulak noted:

[B]y 2020, eighty-five percent of the world’s inhabitants will be crowded into coastal cities—cities generally lacking the infrastructure required to support their burgeoning populations. Under these conditions, long simmering ethnic, nationalist, and economic tensions will explode and increase the potential of crises requiring U.S. intervention.

Back to the Cities

The centrality of cities in Iraq after the 2003 U.S. invasion soon forced renewed thinking about protracted operations in urban areas with an emphasis on protecting the population within a counterinsurgency context. This was a different problem than in past urban battles since the Cold War, which were generally short by comparison, e.g., fights in Grozny, Mogadishu, and Gaza.

Operations in Baghdad, Fallujah, Sadr City, Mosul, and elsewhere in Iraq began a shift in thinking about urban operations. Doctrine now emphasizes their strategic importance, but also focuses on the importance of tactical actions, e.g., small unit actions, precision engagement, minimizing collateral damage, and protecting the population as imperatives in these fights. Furthermore, the services are developing technological solutions for these challenges. The Marine Corps solicitation mentioned earlier notes its interest in technologies, including those “capable of displaying friendly, enemy (indicates criminal, potential enemy, conventional, special operations forces, militia), and local population,” and to enable “the ability to traverse urban canyons, over walls and structures, in subterranean corridors, over buildings, and through structures.” The Army’s Research, Development and Engineering Command is now overseeing a U.S. Army Subterranean and Dense Urban Environment Materiel Developer Community of Practice. In recent tabletop exercises, this group wargamed some 48 different experimental future technologies in different urban scenarios.

Nevertheless, all of these ongoing discussions take it as a given that the U.S. military will be conducting offensive operations in large urban areas in the future. And most of these discussions focus on irregular adversaries. This is not surprising, given that the experiential basis for much of the U.S. military in urban operations has happened since 9/11. Thus, Milley’s characterization of “fighting in Aleppo in Syria, and Fallujah and Mosul in Iraq as ‘previews’ of future conflict” is understandable. Indeed, these types of operations against irregular adversaries are certainly possible. But, so are others.

What Problem Forces the Fight to Cities?

If we take as truth that the U.S. military will have to fight in urban areas, then the first question to ask is what will bring U.S. forces to urban areas in the first place? In short, what is the mission? I believe that the historical record shows that there are two basic offensive missions in urban combat.

A city is a military objective that must be taken and cleared of either enemy military forces or terrorists. The enemy is a cancer that must be removed. This was the case in the urban fights in World War II, the Korean War, the Vietnam War, the Chechen Wars, and various operations in Iraq after Operation Iraqi Freedom and during the war against the Islamic State. In these fights, cities have sometimes been “destroyed to save them.”

Nevertheless, there are examples when the going into the city was not required to deal with the mission of defeating the adversary. These include the 2008 Battle of Sadr City and Israeli operations in Gaza where defeating enemy fighters without entering the city was the mission. Or, the 2017 case in the battle for Tal Afar when “an escape corridor for the trapped fighters, who they hoped would flee into the open desert where they could be picked off.” In these cases defeating the enemy by offensive action with as little damage to the city as possible was the objective.

Finally, given the fact that the National Defense Strategy discusses the use of blunting forces as part of a competition and deterrence posture, defending cities might be the mission. This is a combat operation that U.S. forces have not executed against a high-end competitor since the World War II battles of Bastogne and St. Vith in late 1944.

Who Are You Fighting?

If it is a given for this discussion that the “where” of the fight is a large urban area, the adversary and their capabilities are critical areas for analysis. This is particularly instructive from the perspective of past U.S. experiences as the challenge moves from a focus on irregular adversaries to peer competitors.

The last time the U.S. military fought a peer competitor in a city was during the American Civil War in the Battle for Fredericksburg, if “peer” implies an adversary with roughly equivalent capabilities. Most of the World War II urban battles in which the United States was involved were against adversaries who were no longer peers, because they could not gain air superiority. Indeed, they were generally forces left behind to slow the Allied advance across Europe towards Germany or deny key assets like a port, as during the battles for Cherbourg and Antwerp, or to inflict casualties as in the bloody fight for Manila. The battles in Seoul during the Korean War, Hue during the Vietnam War, and all the urban battles in Iraq, were all against non-peer adversaries who could only contest the land domain.

This will likely not be the case in future conflicts against peer competitors. Russia and China have formidable capabilities that will contest U.S. and partner operations across all domains. Thus, many of the technologies the Army and Marine Corps are pursuing, while very useful against irregular adversaries, may be less useful against peers.

Where Are You Fighting?

It is also important to think about where offensive urban combat operations might occur. A good place to start is with an assessment of the priority countries identified in the National Defense Strategy — China, Russia, North Korea, and Iran.

It is difficult to imagine offensive ground operations in Chinese or Russian cities, given their escalation options (including nuclear). Given Iran’s geography, offensive ground operations in cities in that country are also not likely. In a Korean conflict, potential missions for U.S. ground forces in South Korea in urban centers include assisting in the defense of that country, noncombatant evacuation operations, conducting post-conflict operations to secure North Korean weapons of mass destruction, or assisting in dealing with the consequences of the collapse of the North Korean regime.

In Eastern Europe, where RAND has wargamed the defense of the Baltics, there are no large cities, much less megacities. Indeed, the combined population of the Baltic countries of Estonia, Latvia, and Lithuania at approximately 6 million is less than the 10 million mark for a megacity. Warsaw, the largest city of a NATO member near the Baltics, has a population of 2,300,000. Thus, in the area where U.S. ground forces are most likely going to have to deter Russian aggression, offensive urban operations are unlikely, as will be discussed later.

When the Gloves Come Off

One further issue that needs to be understood in peer warfare: the conflict is not principally about protecting the population, but about killing or capturing the enemy. This is not to say efforts are not made to evacuate populations at risk or to protect noncombatants. They are. U.S. forces, however, have become conditioned over the past decades of irregular war to do everything possible to avoid civilian casualties and collateral damage, given the tenets of counterinsurgency. This is the right thing to do in these kinds of wars but may not always be possible in urban combat when the enemy chooses to fight to the death. The fighting in Fallujah in 2004 and more recently Mosul demonstrated that firepower is often needed to defeat determined irregular adversaries. The Law of Armed Conflict is much less restrictive than the rules of engagement that U.S forces have employed for decades. Others are less restrained in city combat even within the context of fighting irregulars as seen in Russia’s approach in Chechnya. It is reasonable to assume that combat in cities against competent, well-armed state adversaries will be deadly and highly destructive. As Gen. William T. Sherman stated during the U.S. Civil War: “War is cruelty, and you cannot refine it.” Urban combat between peers is perhaps the cruelest of all.

Unasked Questions

There are important questions that should be asked and answered as the U.S. military considers future urban operations.

First, in what kinds of urban operations will the U.S. military be involved? Will they be offensive or defensive combat operations? Against peers, hybrid, or irregular adversaries? Will they be Humanitarian Assistance and Disaster Relief operations in a megacity like Dhaka under noncombat conditions? Or a non-combatant evacuation operation in Seoul in the midst of conflict? Or counterterrorism and contesting violent extremist organizations in urban areas like Mogadishu? Is urban combat going to be largely confined to non-peer adversaries that are a cancer that must be removed, like in Hue, Grozny, Aleppo, Fallujah, and Sadr City?

Second, in irregular urban combat what will be the role of U.S. forces? Will these operations involve U.S. ground combat forces, or will the future resemble Mosul and Raqqa with indigenous ground forces executing most of the close combat, supported by U.S. advisors, fires, and other enablers? Or will Gaza and Sadr City be the norm, where ground forces drew the adversary out of the city and used intelligence, surveillance, and reconnaissance systems, coupled with precision strike, to defeat enemy indirect fire capabilities and direct fire engagements to kill enemy fighters. All while avoiding going into the enemy’s densely populated urban areas, because of concerns about friendly and civilian casualties and collateral damage.

Finally, in thinking about deterring and fighting peer adversaries is enough attention being paid to defensive urban operations, for example blunting forces that turn cities into hedgehogs to deny a Russian fait accompli in Eastern Europe?

This leads to a larger point. Much of the area in Eastern Europe where U.S. forces could play a key role in deterring Russian aggression has no large urban centers. Blunting a cross border invasion of the Baltics — aside from possibly anchoring the NATO defense in Riga, Vilnius, and Tallinn — would largely occur in rural areas that extend from the Russian border to the capital cities. Ironically, this flies in the face of the assertion by former U.S. Secretary of Defense Robert Gates that “the prospects for another head-on clash of large mechanized land armies seem less likely.” Tell that to the Ukrainians.

Thus, before going all-in on optimizing for urban operations, the U.S. military should take a deep breath for a moment and think carefully about future operations within the context of the National Defense Strategy.

This thinking — and the answer to the questions earlier posed — could best be framed by examining the place, the adversary, and the adversary’s capabilities within the context of the mission. This analysis will be key to preparing the U.S. military for future operations, be they urban or something very different.

David Johnson is a retired Army colonel. He is a principal researcher at the nonprofit, nonpartisan RAND Corporation, an adjunct scholar at the Modern War Institute at West Point, and an adjunct professor at Georgetown University.

Image: U.S. Army photo by Sgt. Randis Monroe