Introduction: How to Think About Modern Warfare

This commentary is part of a report from the CSIS Defense and Security Department entitled War and the Modern Battlefield: Insights from Ukraine and the Middle East.

It is a long-standing habit of military historians to describe changes in warfare in terms of two biological paradigms: more or less steady evolution on the one hand and punctuated equilibrium on the other.¹ The messy truth is in between. Sometimes the practice of war—its art and science, the sources of military strength and weakness—advances by fits and starts, and sometimes it evolves at a steady pace.

It is reasonable to assert that the world is at a junction at which war is changing rapidly and that the pure evolutionary model no longer suffices. A confluence of political, social, and technological changes have collectively made war something very different than the practitioners and theorists of the Cold War expected and understood. That is why this collection of studies is so important: There are very large changes underway which have to be understood from multiple perspectives and which resist simple characterization.

The Cold War saw different forms of conflict: irregular wars, which characterized the end of the European empires and their sequels (as in Vietnam), and short, sharp conventional conflicts (as in the 1967, 1973, and 1982 Arab-Israeli wars, the 1971 India-Pakistan War, or the China-Vietnam war of 1979). These wars could be very costly, with casualties in the tens of thousands and possibly more, but by and large they were relatively brief and contained.

The conflicts occurring today in Ukraine and the Middle East have changed that paradigm. These have been two large and protracted wars, lasting not weeks or months but years. They have involved enormous damage to civilian infrastructure and opposed not individual actors but large coalitions of states assisting proxies or clients. Whereas the wars of the late twentieth century involved one-sided dominance of the air, in these wars, missiles, drones, and occasionally aircraft are able to penetrate deep into enemy territory. These wars are different.

Through them, the United States and its allies have rediscovered some old truths—chief among them the importance of industrial production of end items and munitions. In 2022, the United States’ entire monthly production of 155 mm artillery rounds amounted to only somewhat more than what Ukraine expended every day—and considerably less than Russia’s daily rate of use. European allies were even worse off. Even Russia, which had retained an industrial mobilization model for war production, has not been able to meet the demands of the Ukraine war and depended on poorer but industrially deeper clients, like North Korea and Iran, to make up the shortfalls.

Similarly, the West has rediscovered the phenomenon of irregular—or as we now prefer to call it, hybrid—warfare. All wars, including the World Wars, have included the extensive use of propaganda, subversion, and proxy and guerrilla warfare. In no case were these factors sufficient to change the fundamental balance of power, but they played their part nonetheless. However, these elements are playing an increasing role in contemporary warfare.

The nuclear dimension of strategy has also reappeared after a hiatus of more than a generation. While fears of nuclear proliferation helped trigger the Second Gulf War in 2003 and concerns about the North Korean and Iranian nuclear programs have been important in U.S. foreign policy, nuclear weapons played only a minor role in the strategic thinking of the United States and other large powers from the end of the Cold War through the 2020s. That is no longer the case. The rise of China’s nuclear arsenal is one reason for this: China had doubled its number of nuclear warheads in the last decade, and it looks to double them again by 2030. As a result, the United States now faces two potential nuclear opponents that equal or may even overmatch it. Even more troubling, the disruption of the United States’ European alliances brought about by the Trump administration may very well launch a cascade of proliferation that will reshape geopolitics, for example, if countries like Poland and Finland feel they can no longer trust a U.S. deterrent.

There are, however, genuinely new developments in the techne of war. The widespread use of unmanned systems in the Ukraine war is a notable example. Some of the first drones appeared at the end of World War I—most notably the Kettering Bug—and they sporadically reappeared during World War II and in Vietnam. The first major use came in the 1982 Israel-Lebanon war. But the Russia-Ukraine war (like the Azeri-Armenian war of 2020) saw a massive development in drone warfare: a change in quantity that became a change in quality.

From a few hundred unmanned aircraft systems (UASs) at the beginning of the war, Ukraine began deploying thousands, then tens of thousands of drones, and is now manufacturing millions annually. Russia, of course, followed suit. The pattern of ground combat changed, as a UAS-saturated battlefield paralyzed vehicular movement, while an entire fleet—Russia’s Black Sea Fleet—has suffered greater than 30 percent losses and was stopped in its tracks by the attacks of unmanned surface and subsurface systems.² Unmanned ground-based systems have also begun to appear, which will no doubt evolve and proliferate as well.

The deployment of various forms of AI in a military context is also a genuine innovation that has become pervasive. Automatic target recognition and the processing of vast quantities of data has enabled Israel to conduct orders of magnitude more strikes in its wars with Hamas in Gaza and Hezbollah in Lebanon than it could have otherwise. Not only does AI enable the unmanned systems revolution, but it has increasingly transformed tactical- and even operational-level decisionmaking, with consequences for the degree of human control of combat in all of its domains.

It is reasonable to expect that soon enough even terrorist organizations will be able to launch swarms of drones that cooperate with each other to attack targets. Indeed, such a capability probably already exists. The use of sophisticated facial recognition and other targeting software means that the barriers to extensive assassination campaigns, once the prerogative only of the United States, will lessen. The planning and execution of long-range attacks enabled by AI will not completely level the playing field for war, but it will go a long way toward it.

War is changing in other respects as well. It has expanded to new realms, chiefly space and cyberspace. Space-based systems first played an important role in the 1991 Gulf War, but the consequences were one-sided and largely confined to reconnaissance, navigation, and communications. However, the recent explosion in satellite numbers is remarkable. In 2015, there were about 1,400 active satellites in orbit; in 2025, there are over 10,000, and the next decade may see that number quintupling.³ Already, all countries can make some use of space for communications, navigation, and reconnaissance whether or not they possess their own satellites. Further, the potential now exists for actual warfare in and from space, including kinetic and non-kinetic attacks on satellite systems and the delivery of kinetic weapons from space to Earth. Compounding this spread of space-based capabilities is the increased (if murky) interest of great powers in the use of space as an area of combat; the temptation of blinding an opponent, or delivering unanswerable strikes from outer space, may be too much to resist in the next war.

Meanwhile, conflict in cyberspace is now constant—albeit with spikes at particular moments, such as during the first months of Russia’s invasion of Ukraine in 2022 or in the Russian attack on Estonia in 2007. What remains to be seen (but will almost surely occur) is the use of cyberattacks to conduct lethal forms of sabotage.

For the United States, all of these changes come at a time when its strategic predicament has become more global and multifaceted. Three large geopolitical challenges have emerged. The first of these is a coalition of hostile powers—China, Russia, Iran, and North Korea—that collude in several respects and have a common objective of bringing U.S. predominance to an end. Their collaboration across multiple domains—like the deployment of North Korean troops and Iranian drones to fight Ukraine, the sharing of advanced military technology and production, cooperation in disinformation campaigns, and probably sabotage operations against the West—is a challenge unparalleled since the early days of the Cold War.

The second challenge, which results from both geopolitics and technology, is the return of the threat of global war. Particularly after the Cold War, the U.S. military got into the habit of thinking about war as a regional matter, chiefly in the Middle East. Even as China rose, the United States continued to mostly conceptualize the challenge as a regional one in the Indo-Pacific. But because of the size of China’s economy, the expanding nature of its forces, and the evolution of technology—as well as the emergence of the coalition described above—it is likely that a war with China would be global. Hypersonic missiles, space-based weapons, and long-range naval forces coupled with sabotage and covert action mean that even the U.S. mainland would be vulnerable for the first time since the nineteenth century.

Most troubling of all, the United States is no longer the dominant power it once was. To be sure, its relative decline has been exaggerated: Its military remains large and capable, and its share of global economic production (roughly one quarter) has been stable over a generation. Its research and development base remains unequalled, and its basic material ingredients of national power—geographical position, natural resources, and economic and financial strength—are substantial.

But with China, in particular, the United States faces a rival unlike any since Nazi Germany—and that confrontation occurred in a world where the next two leading powers, Great Britain and the Soviet Union, were U.S. allies. The Chinese economy is smaller than that of the United States, but not by an order of magnitude; increasingly, China’s technological capabilities are comparable, and its manufacturing and shipbuilding base considerably superior. In such a world, the United States, with the many vulnerabilities created by its main source of strength—its open society—may be liable to receiving shattering surprises of a kind that have not occurred since Pearl Harbor.

One of the great imponderables is what war will look like when all the dimensions, new and old, are woven together—information operations, irregular warfare, cyberattacks, space warfare, and even conceivably biological and nuclear warfare. It would be unlike anything experienced before in scope and scale, even World War II.

In the essays that follow, CSIS scholars consider many dimensions of the changing character of war. Throughout, it is important to consider not just technology, which may evolve at tremendous speed, but also the relationship between the technical means of war, the politics that underly conflict, and the psychology of those who must direct it.

For example, historically it has been assumed that a large population of young people—and specifically young men—was essential for the waging of war. It is reasonable to ask whether the vast proliferation of unmanned weapons systems, and the reversion of humans to their direction and control, reduces the significance of demographic disadvantage. Or consider how old modes of warfare waged with new techniques have different efficacy because of new conditions. At one level, information warfare is as old as war itself. Propaganda and disinformation played their roles in the eighteenth century as much as the twentieth. But in an age of fragmented media, deepfakes, and bots, they may have a significantly different and possibly larger role to play.

Finally, technology will affect how political and military leaders—whose essential human characteristics, after all, have not evolved—direct war. Since the middle of the nineteenth century, modern technology has made it ever easier for leaders to exercise direct supervision and control over forces on the battlefield. Yet the nature of war remains: chaos and confusion are generated (as Clausewitz pointed out) not by the physical smoke over the battlefield but by the pressures it generates. There is no guarantee that new technologies will improve the quality of wartime leadership. Indeed, they may actually serve to weaken it.

In sum, the world of war that may emerge in the remaining three-quarters of the twenty-first century is more extensive, less comprehensible, and possibly even more devastating than anything humanity has ever known. That alone should be enough to compel its study with the utmost care—and to that end, these essays are an excellent beginning.

Outline of the Report

This report is divided into three primary sections. The first addresses the implications of the conflicts in Ukraine and the Middle East on war at the strategic, political, and societal levels. Chapter 1 argues that there is likely to be a deepening of relations going forward among U.S. competitors and adversaries. Chapter 2 demonstrates that societal resilience is a critical and integrated aspect of national security, which strategic planners should not relegate to a secondary consideration. And modern warfare for allies and adversaries alike will increasingly rely on nuclear weapons, as Chapter 3 articulates.

The second section of the report assesses the future of warfare in operations, tactics, and technology, addressing the implications of the current wars on particular domains and capability areas. Chapter 4 provides an overview of the impact of battle networks on operations before Chapter 5 highlights the continued significance of landpower in war. Chapter 6 argues that the experiences in Ukraine and the Middle East show that reigns of fire will endure, as offensive and defensive fires remain critical to combined operations. Technological advances, massive data analysis, and open-source intelligence have changed the world of intelligence and spycraft, as depicted in Chapter 7, but they have also contributed to a blurring of lines between state, industry, and academic actors.

Chapter 8 argues that the war in Ukraine has been a turning point in the role of space in warfare, demonstrating how space capabilities can create an advantage over a more capable military power. Other emerging technologies will push future conflicts into a competition of who can evolve and innovate more quickly, according to Chapter 9. This may be particularly true in the air domain, where Chapter 10 argues that AI-enabled decisionmaking will play an increasingly important role in a challenging environment shaped by increasingly sophisticated and diverse sensors. In the naval domain, Chapter 11 identifies that the Ukraine and Middle East wars, despite being predominantly land campaigns, yield some notable insights for current action, including expanding munitions inventories, accelerating uncrewed systems, and hedging on major surface combatants. Chapter 12 argues that the ongoing wars demonstrate that irregular warfare is not a relic of the past but a defining feature of contemporary conflict.

The third section of the report addresses implications for defense budgets, logistics, and acquisition. Chapter 13 discusses the growth in global defense spending among allies and competitors and trends in procurement patterns. Chapter 14 argues that logistics is more critically important today than in the past, and Chapter 15 addresses how industry must evolve given the acquisition patterns in conflicts in Ukraine and the Middle East. The report concludes by discussing how prepared the United States is for competition, deterrence, and warfare in this new era of conflict.

Please consult the PDF for references.

Eliot A. Cohen is the Arleigh A. Burke Chair in Strategy at the Center for Strategic and International Studies in Washington, D.C.