Europe is a landscape; East Asia a seascape. Therein lies a crucial difference between the 20th and 21st centuries.
The most contested areas of the globe in the last century lay on dry land in Europe, particularly in the flat expanse that rendered the eastern and western borders of Germany artificial and exposed to the inexorable march of armies. But over the span of the decades, the demographic and economic axis of the Earth has shifted measurably to the opposite end of Eurasia, where the spaces between major population centers are overwhelmingly maritime.

Because of the way geography illuminates and sets priorities, these physical contours of East Asia augur a naval century - naval being defined here in the broad sense to include both sea and air battle formations now that they have become increasingly inextricable. Why? China, which, especially now that its land borders are more secure than at any time since the height of the Qing dynasty at the end of the 18th century, is engaged in an undeniable naval expansion. It is through sea power that China will psychologically erase two centuries of foreign transgressions on its territory - forcing every country around it to react.

Military engagements on land and at sea are vastly different, with major implications for the grand strategies needed to win - or avoid - them. Those on land enmesh civilian populations, in effect making human rights a signal element of war studies. Those at sea approach conflict as a clinical and technocratic affair, in effect reducing war to math, in marked contrast with the intellectual battles that helped define previous conflicts.

World War II was a moral struggle against fascism, the ideology responsible for the murder of tens of millions of noncombatants. More recently, a moral struggle against radical Islam has drawn the United States deep into the mountainous confines of Afghanistan, where the humane treatment of millions of civilians is critical to the war's success.

In all these efforts, war and foreign policy have become subjects not only for soldiers and diplomats, but for humanists and intellectuals. Indeed, counterinsurgency represents a culmination of sorts of the union between uniformed officers and human rights experts. This is the upshot of ground war evolving into total war in the modern age.

East Asia, or more precisely the Western Pacific, which is quickly becoming the world's new center of naval activity, presages a fundamentally different dynamic. It will likely produce relatively few moral dilemmas of the kind we have been used to in the 20th and early 21st centuries, with the remote possibility of land warfare on the Korean Peninsula as the striking exception. The Western Pacific will return military affairs to the narrow realm of defense experts. This is not merely because we are dealing with a naval realm, in which civilians are not present. It is also because of the nature of the states themselves in East Asia, including China.

The struggle for primacy in the Western Pacific will not necessarily involve combat; much of what takes place will happen quietly and over the horizon in blank sea space, at a glacial tempo befitting the slow, steady accommodation to superior economic and military power that states have made throughout history.

East Asia is a vast, yawning expanse stretching nearly from the Arctic to Antarctic - from the Kuril Islands southward to New Zealand - and characterized by a shattered array of isolated coastlines and far-flung archipelagos. Even accounting for how dramatically technology has compressed distance, the sea itself still acts as a barrier to aggression, at least to a degree that dry land does not. The sea, unlike land, creates clearly defined borders, giving it the potential to reduce conflict.

Then there is speed to consider. Even the fastest warships travel comparatively slowly, 35 knots, say, reducing the chance of miscalculations and giving diplomats more hours - days, even - to reconsider decisions. Navies and air forces simply do not occupy territory the way that armies do. It is because of the seas around East Asia - the center of global manufacturing as well as rising military purchases - that the 21st century has a better chance than the 20th of avoiding great military conflagrations.

Of course, East Asia saw great military conflagrations in the 20th century, which the seas did not prevent: the Russo-Japanese War; the almost half-century of civil war in China that came with the slow collapse of the Qing dynasty; the various conquests of imperial Japan, followed by World War II in the Pacific; the Korean War; the wars in Cambodia and Laos; and the two in Vietnam involving the French and the Americans.

The fact that the geography of East Asia is primarily maritime had little impact on such wars, which at their core were conflicts of national consolidation or liberation. But that age for the most part lies behind us. East Asian militaries, rather than focusing inward with low-tech armies, are focusing outward with high-tech navies and air forces.

As for the comparison between China today and Germany on the eve of World War I that many make, it is flawed: Whereas Germany was primarily a land power, owing to the geography of Europe, China will be primarily a naval power, owing to the geography of East Asia.

Robert D. Kaplan (Foreign Policy)
Robert D. Kaplan is senior fellow at the Center for a New American Security, national correspondent for the Atlantic, and a member of the U.S. Defense Department's Defense Policy Board. He is the author of Monsoon: The Indian Ocean and the Future of American Power.