Hal Brands
Hal Brands is the Henry A. Kissinger Distinguished Professor at the Henry A. Kissinger Center for Global Affairs at Johns Hopkins University's School of Advanced International Studies and a senior fellow at the Center for Strategic and Budgetary Assessments. His latest book is "American Grand Strategy in the Age of Trump."

Afghanistan Was a Limited War With Limited Success

Another limited war, another unsatisfying outcome. The US is on the brink of withdrawing from Afghanistan, just shy of 20 years after it invaded that country, and well short of any desired resolution. At best, America will leave behind a mess; at worst, withdrawal may precipitate strategic setbacks and a humanitarian disaster.

That legacy will be seen as a commentary on America’s post-9/11 wars — conflicts, critics allege, that were launched in a fit of unipolar hubris. But Afghanistan fits within a larger pattern. The US has a long, checkered history in wars fought with limited means for limited aims, simply because these are the conflicts in which it is hardest for a superpower to succeed.

Wars differ significantly in their intensity, goals and conduct. At one end of the spectrum are total wars in which societies mobilize nearly all of their resources and seek the total destruction of the enemy: Think of World War II or the wars that followed the French Revolution. Toward the other end of the spectrum are limited wars in which a combatant mobilizes a fraction of its resources, seeks something less than total victory, and accepts constraints on how it fights.

The US has fought plenty of limited conflicts. There have been big ones, such as Cold War-era fights in Korea and Vietnam, meant to defeat aggression in peripheral areas. There have been smaller limited wars, such as the US intervention in Lebanon in the early 1980s or occupations of Latin American countries in the early 20th century, meant to bring stability to unstable parts of the world.
And there have been the post-9/11 wars, conflicts in which the US — using an all-volunteer military drawn from a tiny minority of the population — sought to defeat terrorist groups and combat insurgencies without putting the country on a war footing.

As these examples indicate, the US has often found limited war to be a vexing experience, for two main reasons.

First, because the stakes (for the US) are considerably less than existential, Washington typically harnesses only a sliver of the country’s overall resources and power. It pulls punches in dealing with weaker enemies: Even in Korea, the US didn’t use nuclear weapons or expand the war into China.

There are often good reasons for these constraints. In Korea, the US feared setting off a much bigger war with the Soviet Union. But America thus finds itself at a relative disadvantage against enemies for whom the stakes are often closer to total.

Second, limited wars are conflicts in which a frustrated superpower is most likely to give up and go home. In the early stages of World War II, the US suffered appalling military defeats, but it simply kept fighting to decisive victory. In limited wars, the stakes are lower, and so it is more tempting to accept ambiguous or unpalatable results — a bloody draw in Korea, outright defeat in Vietnam, withdrawal under fire in Lebanon. That dynamic, in turn, leaves Washington vulnerable to crafty, committed opponents who are willing to suffer exorbitant losses in hopes of wearing down America’s will over time.

In these respects, the war in Afghanistan is not so unusual. The Pentagon never used more than about 100,000 troops (accompanied by a smaller number of allied forces) in that country, and that “surge” was but a blip in the history of a 20-year campaign. The US always fought within tight political constraints — choosing not to target the Taliban’s bases in Pakistan, for instance, and calibrating the level of force that could be used without alienating the Afghan population. The Taliban absorbed horrific human losses, but inflicted costs that an overstretched global superpower eventually tired of paying.

Does this mean the US should never fight limited wars? Not really.

Limited wars are typically kept limited for sensible purposes: To avoid catastrophic escalation, to prevent an out-of-the-way conflict from monopolizing America’s power and attention, to avoid using tactics that would shock the conscience of a democratic society. And simply abstaining from limited uses of force would leave the US unable to defend its interests against an array of violent challenges.

Admittedly, some of America’s limited wars (most notably, Vietnam) were strategic failures by any reckoning. But others, such as Korea, resulted in more success than failure, by stymying communist aggression that could have seriously destabilized a fragile postwar world. Still others, such as Afghanistan, sit somewhere between the two. All of which means that the careful exercise of strategic judgment, however imperfect, is a better prescription than some blanket prohibition.

For better and for worse, being a global superpower involves fighting conflicts that matter a great deal more to the enemy than they do to the US. The frustrations that America has encountered in Afghanistan aren’t a product of post-9/11 delusions: They are more normal than either critics or supporters of that mission might like to admit.