“I said O.K.,” Jalil said.

The screen flashed again. Another Afghan appeared, younger than the first. His name was Niaz, a resident of Mirwais Mena. His nickname, he told the camera, was Bango. In Pashto slang, “bango” means “hashish.” On an evening in early November, Bango, 18, said, he drove his motorcycle to see Jalil and two other men he’d never met, Naim and Torjan. Jalil handed the two men $1,200 each. They would spray the acid. Torjan handed Bango $125. He would drive.

“When Torjan started spraying the first girl, I stopped my bike, but he told me to keep moving,” Bango said into the camera. “So I kept moving, and he sprayed another group of girls in the middle of the road.”

The screen flickered again. This time, an Afghan girl appeared, writhing in a hospital bed. She was covered in bandages. The scene changed again; the same girl reappeared, this time seated at a table. She wore a white head scarf, but the scars were still visible, rimming her eyes in a bright mask and spreading across her cheek. A caption gave her name as Shamsia Husseini.

“We want them to be executed in front of us,” Shamsia said. She spoke calmly and slowly. “The same way they sprayed acid on us, we want acid sprayed on them.”

After a while, the screen went dark.

EIGHT YEARS AFTER the Americans came to Afghanistan, it is hard to find reasons to be optimistic about the future. In November 2001, when the Taliban clerics fled Kabul, the country lay in ruins. Today, it still does. Outside Kabul, there is hardly any government to speak of. There are governors, there are some police authorities and there is very little else. The roads are mostly broken and unpaved. Warlords hold much of the country in their hands. The goodwill that flowed so freely eight years ago has mostly disappeared, drained away by the failure to rebuild the country, to crush the Taliban and to do so without slaughtering innocents. It is easy to give in to despair.

And yet if there is one unambiguously positive change that the American-led enterprise has brought it is the education of girls. In 2001, only a million Afghan children were enrolled in school, all of them boys. The education of girls was banned. Today, approximately 7 million Afghan children attend school, of which 2.6 million, or roughly a third, are girls.

As a correspondent in the late 1990s, I traveled often to Afghanistan when the Taliban were in control. The country was a grim and medieval place — I witnessed a public execution at a Kabul stadium. In July 2000, when the Taliban were at the height of their power, secret schools for girls were springing up across the country. The women and men who ran these schools, often out of their own apartments, risked horrible punishments. One afternoon in Kabul, on my way to meet some parents who were running one such school, I was descended on by the Taliban’s vice-and-virtue police. I was arrested and expelled from the country. I didn’t return to Afghanistan until after 9/11.