Their outrage, however, is unconvincing. Those same Afghans, and the Northern Alliance opposition forces they support, are now counting on Taliban defections to help regain their lost land. To them, such a turn would only be wise.
Changes of heart are a way of war in Afghanistan. Among today's Taliban forces are regional warlords who once fought against the Islamic fundamentalist movement. Among today's opposition Northern Alliance are fighters who only weeks ago answered to the Taliban.
"They do not look at this as betrayal, this jumping sides," said Alexander Chamagayev, a Tashkent analyst who specializes in Afghan history and politics. "Each commander, each fighter there, they don't know what will happen the next day and so each has to watch out for his own interests. It is very calculated."
Local warlords and even frontline soldiers are sometimes paid to cross over. The Taliban took full advantage of this tradition as its fighters consolidated their grip over Afghanistan in the late 1990s.
But personal benefit is not the only factor. Many commanders are loath to inflict much bloodshed or see it inflicted on their own men. Better to cross the line than suffer a bruising battle likely to end in defeat or provoke years of bitter recriminations.
That apparently was the thinking of Nuruddin, one of many Afghan fighters who goes by one name. For years the rebel commander was fighting Taliban forces as they swept north of Kabul and gobbled up land leading to Mazar-e Sharif. But then the Taliban just got too strong.
"We were surrounded. We were cut off," said Abdul Hakim, a Nuruddin aide who recalled the fix he and his comrades found themselves in back in 1998 as the Taliban laid siege to Mazar-e Sharif. "The commander decided we should swap sides temporarily to save our lives. So we had negotiations with the Taliban. And then they sent some people who told us we would not be arrested."
Until a few weeks ago, Nuruddin and his men had stayed with the Taliban even as some of them were maintaining contacts with the Northern Alliance. Then a falling out with other Taliban-aligned forces, punctuated by a nasty and fatal shootout, sent Nuruddin, his men and control of a vital roadway back over to the opposition.
"In our hearts, we were not on [the Taliban] side," Hakim said at an opposition base camp in northern Afghanistan.
Such talk motivates the Northern Alliance, which has been welcoming small groups of defectors along the Kabul line and some bigger groups in the north.
Opposition forces are outmanned and outgunned along most Taliban front lines. They are counting on U.S. bombing raids to soften up Taliban defenses and also to convince Taliban rank and file that they are backing the losing side. Should that happen, the opposition says, defections could snowball.
Waiting for defectors
Mohammad Hasham Saad, the top official for Afghanistan's government-in-exile in Tashkent, said the Northern Alliance hopes eventually to surround Mazar-e Sharif and then wait out wavering Taliban forces until they just switch.
"We don't want to take so many casualties," Saad said, making it clear that he meant fighters on both sides as well as civilians. "We have been in negotiations with some Taliban commanders from the north. We will continue talking with them."
The Northern Alliance negotiating position, at least around Mazar-e Sharif, was a lot stronger before a Taliban counterattack pushed the rebel troops back several miles from the city limits. Swaying the Taliban will be a lot harder now that the threat is, basically: "You have us surrounded. Join us."
Beyond that, the Arab and Pakistani fighters who supplement and sometimes command Taliban units are unlikely to engage in the kind of fair-weather fighting the Afghans have favored. The same goes for the ideologically inspired Taliban troops who see this fight as a holy war.
Yet if the Northern Alliance can resupply with American and Russian help, and if the American bombing raids can weaken the resolve along the Taliban front lines, then the rebels could start bringing into their fold their current enemies. Especially if some of those enemies were once the rebel friends.
"This is the way the Afghans fight among themselves," said Chamagayev, the Tashkent analyst. "They do not want a bloodbath."
Quickly, then, Chamagayev added a caveat. This practicality among the Afghan warrior applies to a civil war. Should foreign troops invade, Chamagayev said, no one should expect the Afghan fighters to jump from side to side.