The USS Gerald R. Ford in April 2017. (Mass Communication Specialist 2nd Class Ridge Leoni/U.S. Navy via AP)

Robert D. Kaplan is managing director for global macro at Eurasia Group and a member of the Chief of Naval Operations’ Executive Panel. He is the author of “The Return of Marco Polo’s World: War, Strategy, and American Interests in the Twenty-first Century.”

President Trump’s decision to withdraw the bulk of U.S. troops from Syria and Afghanistan has found grudging support among sectors of the foreign policy establishment and the Democratic Party. Clearly, out of a sense of collective fatigue, we are ending an era of land interventions in the Middle East that began with the 1991 liberation of Kuwait by President George H.W. Bush. At a cost of 7,000 lives and several trillion dollars for remarkably little demonstrable result, those interventions have not been a happy experience. The admonition about never fighting a land war in Asia could also be applied to the Middle East.

After 28 years of land wars in the Middle East, counterinsurgency doctrine is now for the bookshelves: lessons learned the hard way, and always available for use upon the next mistake or quagmire, but hopefully allowed to gather dust. No military service has suffered so much and learned so many lessons as the U.S. Army in Iraq and Afghanistan. But the object of strategy is to avoid its use in such a manner again.

The upshot of this will not be isolationism. Instead, we will project power across large swaths of the earth the way maritime empires have done so throughout history: using our Navy. The Navy is our “away team,” as Obama-era Secretary of the Navy Ray Mabus liked to say. You can move an aircraft carrier strike group — with almost a half-dozen big warships, thousands of sailors and enough weaponry to destroy an entire city — from one conflict zone to another with the media barely noticing. We do it all the time. But to move a commensurate number of soldiers and their equipment is impossible without a debate in Congress, or a front-page headline. Given the moral taboo against the use of nuclear weapons, the Navy is the United States' primary strategic instrument, projecting power 24/7 around the globe. And by Navy, I mean naval power in all its dimensions: sea, air and ship-based missiles.

The Navy, with the indispensable help of the Air Force, can achieve engagement and overbearing influence without quagmires, offering a way to be light and lethal across the globe without getting bogged down anywhere. Large land forces are for contingencies only: that is, unpredictable events and misjudgments that leave us with little choice but to engage on the ground. Yet even if we were to have another war in the Middle East — with Iran, say — we would likely emphasize our Navy, Air Force and Cyber Command, as well as the deployment of missiles and satellites. An exception is the Special Operations community, which enables us to project land power — sparingly, mind you — with relatively few troops through local allies that we train and equip.

A war with China would be mainly naval and cyber. The nature of high-tech war and the shrinkage of the earth through technology is leading to an abstract realm of missiles, space power, surface and subsurface naval platforms, and drones in a world in which conflicts can more easily migrate from one crisis zone to another. The new generation of military correspondents and defense analysts must be able to analyze missile trajectories and count hulls in the water more than boots on the ground. They will have to experience, as I did for many weeks at a time, the monastic, sensory-deprived and claustrophobic surroundings of destroyers and submarines, where the tension is primarily cerebral.

Obviously, there are exceptions. If the Russians were to annex the eastern part of just one of the Baltic states, that could result in a large deployment of U.S. soldiers in a conflict zone. If North Korea were to ever implode, the U.S. Army could suddenly be involved in the mother of all relief and stabilization operations. But again, these and other examples would be contingencies involving only the most vital of national interests: a higher form of necessity than what impelled our ground interventions in the Balkans and the Middle East — however critical those interventions appeared to many at the time.

There is a cruel trade-off here, since the onset of climate change means more — not less — humanitarian catastrophes in the developing world, where the deployment of uniformed troops can sometimes make a critical difference in saving lives, especially in sudden, weather-related emergencies. But unless such interventions are high-profile and short-term, there will be little political appetite for doing them.

There is no going back to the pre-Trump era, not only in politics but also in military affairs. This new era will be far more complex than the last. We have been conditioned to battlefield deaths as the result of snipers, car bombs and block-by-block fighting in places such as Ramadi and Fallujah, Iraq. The future could be even more costly, thanks to the effects of sea-launched missiles and automated battle systems on air and naval platforms — and the fact that great power competition now occurs in a digital age in which the front line is only a click away, encouraging escalatory behavior.

A naval century is upon us, in keeping with an era of globalization that depends on safe and secure sea lines of communication for container shipping. But nobody should assume it will be peaceful. The United States is coming home from tragic wars, but there is little relief in sight.

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