WASHINGTON: What does America need an army for, anyway? The question has bedeviled policymakers since the Founding Fathers, who wrote their distrust of large ground forces into the Constitution. The question returns as budgets come back down after every land war.

This time around, the Army leadership has not given the country a clear answer, which hobbles it in the current budget battles — and perhaps in the next shooting war as well. While the service itself struggles to define its future role, a new Army-sponsored report from the influential Center for Strategic and International Studies here is offering its own answers, answers that push not only civilian policymakers but the Army’s own leaders outside their comfort zone.

The future of ground forces, the study argues, lies somewhere in the “messy middle,” between long-range, high-tech air- and cyber-strikes against a hostile nation-state — the “AirSea Battle” vision of the Navy and Air Force — and low-profile, low-cost Special Operations and drone raids against scattered terrorists. The study, entitled Beyond the Last War, lays out a score of scenarios, half in the Pacific and half in the Middle East, where the problem will be too big for Special Ops alone but too deeply dug in to excise surgically from afar.

“The myth that we’re defeating is the either-or-proposition,” Nathan Freier, the retired Army officer who headed the study for CSIS, said in an interview yesterday. “There’s like this almost binary [worldview]: We’re either going to worry about China and Iran” — well-armed nation-states — “or we’re going to worry about terrorists, and there’s nothing in between.”

“The last three to four months have been pretty instructive on how that’s not necessarily sound,” Freier went on. Just this morning, for example, the Obama Administration and the Iranian-backed group Hezbollah are both, reportedly, moving closer to intervening in Syria.

The study group looked at three Syrian scenarios: a post-Assad incursion to root out terrorists finding sanctuary amidst the anarchy; a clash between a new Sunni-led Syria and Shia Iraq; and a border war with Turkey, which in real life has already requested NATO reinforcements against the spreading conflict. But Freier and company derived, all told, some 20 contingencies from interviews with officers and civilians across all the services, not just the Army, visiting Honolulu, home of the Pacific Command, and Tampa, home of Special Operations Command and Central Command (responsible for the Middle East), as well as agencies in Washington. The hypothetical conflicts range from an Egyptian civil war where the US must protect the Suez Canal and oil pipelines, to an Indo-Pakistani war where the US must enforce a ceasefire after a nuclear exchange, to a North Korean collapse where American must secure loose nukes (also the subject of a recent Army wargame).

All 20 cases are messy and complex. All require significant ground forces, not a radically downsized Army, which is unsurprising given that’s exactly what the Army’s “resource management” staff (known as G-8) asked CSIS to study. What was surprising, at least to Freier himself, was the unifying theme that emerged “relatively late in the process.”

While no one model captures the complexity of all 20 cases, Freier said, the most common and most challenging requirement was for something the study called “distributed security” operations. The idea is in some ways an update of former Marine Corps Commandant Charles Krulak’s “Three Block War,” where US forces must fight for their lives in one location, enforce peace between rival factions in the next block over, and provide humanitarian relief to civilians in the third. But Freier and company’s “distributed security” vision is bigger in scale than Krulak’s and, despite the carefully neutral name, it’s even scarier. It posits chaos on a country-wide scale, where the US must secure some crucial territory — refugee camps, an oil pipeline, nuclear weapons plants — while fending off well-armed regular troops, elusive guerrillas, and hostile local civilians.

If this sounds like Iraq or Afghanistan, it should, because it is — except it’s worse. “Imagine Yugoslavia circa 1994 with oil wells,” Freier told me. “Counterinsurgency would fall into this category, but our sense was that it was likely to be more intense than traditional counterinsurgency. [US forces would have] our backs to something important and our rifles pointed out under a strict and very limited mandate.”

“We don’t suggest that the United Sates is going to conduct serial nation-building exercises around the world,” he emphasized. With civilian and military leaders alike badly burned by ambitious, open-ended commitments in Afghanistan and Iraq, he said, “they’re going to intervene for limited purposes with a very specific objective in mind, and there’s going to be a great deal of restraint on the part of American policymakers”: just look at the last two years of caution over Syria.

Nevertheless, “all the lessons of the last 12 years are still going to be very relevant,” Freier said. “You’re going to have to partner with tribal sheikhs and local authority figures that don’t necessary have a direct, hard link to a central government that is functioning and is a partner of the United States…. You’re not going to benefit from having widespread support of the population, either.”

At the same time US forces must win over local “hearts and minds” for at least short-term alliances, however, they will also have to fight well-armed adversaries. And as dangerous technologies proliferate, those adversaries will have at least some precision weapons and cyber-attack capabilities to threaten US military infrastructure — bases, ports, communications networks — in ways the Taliban simply can’t. They may well have chemical, biological, or even nuclear weapons.

Such a “hybrid” threat may arise as a deliberate strategy. Iran, for example, develops nuclear weapons and buys advanced missile systems for its regular military while its Revolutionary Guard adopts “swarm” tactics with small boats and arms proxy forces like Lebanon’s Hezbollah. Or hybridization may occur by accident, as a well-armed regime collapses and rival factions pick over its arsenal, a nightmare scenario in Syria, North Korea, and for that matter Pakistan.

To defeat such high-end threats will require many of the same capabilities as in conventional war: air support, armored vehicles, long-range missiles, hacker-proof networks, and protection against nuclear, biological, and chemical contamination. But the US will need to wield those tools with more flexibility and in a more decentralized (or “distributed”) manner than against a traditional nation-state opponent. This kind of conflict, warns the study, “is more dangerous and disruptive to US interests than is the distant prospect of large-scale major combat campaigns against conventional military opponents.”

Unfortunately, Freier fears, even while US troops are still fighting in Afghanistan, the military-industrial-political complex is drifting back to its comfort zone of conventional conflict.

“We are experiencing Rumsfeld Revolution Part II,” said Freier, invoking the former Defense Secretary’s failed strategy of high-tech, low-manpower “shock and awe.” These concepts, also known as “transformation” or the Revolution in Military Affairs, have begun to make a comeback as the country wearies of counterinsurgency. The fallacy, Freier said, is not just the longstanding American infatuation with technological solutions but the even older and more widespread post-Westphalian tendency to fixate on the threat of hostile states — Iraq for Rumsfeld; Iran, North Korea, and China today — and underestimate threats posed by either non-state actors or a state’s collapse. Even China, if we ever came to blows, would be more likely to employ what Chinese theorists call “unrestricted warfare” — cyber-attacks on the US financial system, for example — than the kind of conventional warfare the US is most comfortable with.

“The bureaucracy’s strong inclination is to resist change and to focus on the comfortable,” said the Atlantic Council’s Barry Pavel, a veteran of the Pentagon himself, at a CSIS event this morning to roll out the report. “We love to deal with militaries that look like us,” be they the Red Army in the Cold War or the People’s Liberation Army now.

“It would be nice if the world would let us ‘pivot’ towards Asia,” Pavel said, but if we “wish away” the “uncomfortable but plausible scenarios” like those in the CSIS report, “it will come back to bite us.”