A grainy cell-phone video showing a young Afghan woman being executed, reportedly by the Taliban, has sparked an outcry in Kabul and abroad. (A still-disturbing edited version of the clip is below.) Afghan President Hamid Karzai called the men who took part in the killing "cowards," and sent security forces to hunt them down. U.S. Gen. John Allen, commander of 130,000 U.S. and NATO troops in Afghanistan, called the killing "an atrocity of unspeakable cruelty," and women's rights activists held a protest march in Kabul. Could the outrage mark a significant setback for Islamists hoping to regain control over the country? Here, a guide:

Why was the woman killed?

There have been inconsistent accounts about the accusations against the woman, a 22-year-old named Najiba, who was reportedly killed in late June in a village called Qol-i-Heer, about a two-hour drive from Kabul. The militants in the video can be heard saying that the woman deserves to die for committing adultery. A senior provincial official says the adultery charge was fabricated to justify killing the woman, because her husband is a local militiaman who killed a Taliban commander. Roshna Khalid, a spokeswoman for the provincial government, told The New York Times that the woman was killed for having affairs with Taliban fighters.

What does the video show?

Najiba is seen in the background, sitting silently and covered by a shroud. The camera pans around showing dozens of militants and bystanders, all men, watching perched on a dusty ridge and in the dirt street below. Many of the men are armed. One, who appears to be a Taliban judge, announces the verdict of what was reportedly a brief kangaroo court hearing in which the woman was condemned to die. One man says the woman defied God's warning against adultery. "It is the command of Allah that she be executed," another man says. Then someone hands an assault rifle to the executioner — Najiba's husband, by some accounts — who calmly walks up behind her and fires nine shots at close range, killing her. Then people in the crowd shout, "God is great!"

How did Afghans react?

In the village, it's hard to say how people felt. Afghan security forces went there shortly after the report surfaced, but the Taliban fighters had either fled or found shelter in the homes of locals. Security experts say rural Afghans might approve of the Taliban's actions, as they share their hardline take on morality, or they might simply be afraid they will be killed if they speak out against the Islamists. But the tragic incident undeniably stoked anger against the Taliban's treatment of women. "We want the government to take serious action and stop them," Zuhra Alamyar, an activist at the Kabul rally, tells Britain's The Guardian.

Does that mean the backlash is a setback for the Taliban?

It could be. It certainly has energized groups demanding greater freedom for women, whom the Taliban forbid from leaving home without a male guardian. The tragedy has also served as a reminder, observers say, of what life was like under Taliban rule from 1996 to 2001, when public executions, especially for "moral crimes," was commonplace. Still, the taping of the incident sends an ominous message, says Zainab Salbi at CNN. "The Taliban is demonstrating its complete disregard of the Afghan government and the national rule of law," and such a public challenge so close to Kabul shows that the Islamists are confident that they will some day regain control.

Sources: ABC News, CNN, Guardian, New York Post, New York Times

Below is a version of the video of the execution from ABC News. WARNING: The footage of the shooting has been blacked out, but the images are still graphic: