While the presidents of Pakistan and Afghanistan were in Washington last week telling President Barack Obama what he wanted to hear, things back home were busy going from bad to worse.

Pakistani President Asif Ali Zardari took the occasion to declare war on the homegrown version of the radical Islamic Taliban and said he’d ordered the Pakistani military to clear them out of the Swat valley and neighboring areas near the frontier with Afghanistan.

More than 100,000, and perhaps as many as 500,000, Pakistani civilians have now fled for their lives, crossing the border into Afghanistan, of all places, and seeking shelter in refugee camps in Pakistan.

Meanwhile, as Afghan President Hamid Karzai made the rounds in Washington, American military commanders scrambled to investigate Afghan and International Red Cross reports that U.S. airstrikes had killed scores of civilians while targeting Taliban insurgents in western Afghanistan.

The initial U.S. response was to minimize the number killed, claiming that only 50, not nearly 150, had been killed, and that most of them were Taliban fighters. The unfortunate civilian casualties, commanders said, were human shields the Taliban kept close to them during the fighting.

Therein lies the rub. Civilian casualties infuriate the very people whose hearts and minds we’re attempting to win with our stated goal of protecting the people and making their lives better.

Although they haven’t yet begun to arrive, the American military reinforcements ordered in by President Obama can only make that situation worse as they fan out into small remote outposts where their only recourse when they’re attacked is to call in airpower.

Everyone involved in the Afghan riddle pays lip service to the fact that, as in Iraq, there’s no purely military solution. However, eight years of Washington’s benign neglect have allowed the Taliban to grow stronger, fight smarter and become an imminent threat to the government we installed in Kabul.

So before any meaningful nation-building and improvement of the lives of the long-suffering Afghan people can be accomplished outside the city limits of Kabul and Kandahar, the American strategists say we must establish security and at least attempt to seal off the freeways for Taliban fighters commuting from Pakistan.

The chances of achieving anything remotely resembling success with the 50,000-plus American troops that President Obama has approved appear to be somewhere between slim and none.

What, then, are the chances that the Pakistani Army can succeed in its reluctant war against homegrown Pakistani Taliban guerrillas in the rugged North West Frontier Province? Since its inception with independence in 1947, Pakistan’s Army has been trained and equipped to fight a conventional war with neighboring India, not the war it’s grudgingly beginning against the tough tribesmen in those never-conquered mountains.

President Obama has thrown in a lot of chips on this hand, acknowledging as he did so this week that while “there will be more violence, and there will be setbacks,” we will support the governments of Pakistan and Afghanistan.

Almost half a century ago, we had another new president who came to office with an agenda of historic social change and a small, nagging guerrilla war that he inherited from his predecessor. In the end, both the presidency of Lyndon B. Johnson and the man himself were devoured by a war he couldn’t win but seemingly couldn’t find a way to end without looking weak.

There are lessons aplenty to be learned from Vietnam, which consumed the lives of 58,249 American troops, but apparently most of them have now been forgotten.

Here’s a reminder:

—Lesson One: Don’t get in the middle of another country’s civil war.

—Lesson Two: Know and assess your enemy first. Study his history and culture with a sharp eye on his fighting ability — and never underestimate him.

—Lesson Three: Arrogance and ignorance are almost always a fatal combination.

—Lesson Four: If your enemy can seek shelter across an international border where you can’t chase him, then you have just ceded him the strategic initiative. He’ll decide when and where to fight and for how long, and all you can do is react. —Lesson Five: Don’t begin a war without knowing what you hope to achieve and how you intend to get out. —Lesson Six: War is too important to be left to the generals — or to the politicians.

Joseph L. Galloway is a military columnist for McClatchy Newspapers and a former senior military correspondent for Knight Ridder Newspapers; he is co-author of the national best-seller “We Were Soldiers Once ... and Young.” Readers may write to him at: P.O. Box 399, Bayside, Texas 78340.