Although there was speculation that his time in jail radicalized him, Awlaki described a mundane prison term that lasted one and a half years. He complained about the lack of ercise but appreciated the time he had to read the Koran. His first nine months were in an underground cell, eight feet by four with a twelve-foot-high ceiling, and FBI agents were among his only visitors. He was interrogated with "some pressure," Awlaki said, but this wasn't waterboarding: When he complained, the agents supposedly apologized, and during the second half of his term he was given books, pen and paper, a roommate, an aboveground cell three times as large, frequent family visits, and home-cooked meals delivered to the prison twice a week. His bitterest comment was about the lack of sunlight.

The FBI asked about his associates in Yemen and the presence of two September 11 hijackers at his mosque in San Diego. He dismissed any claim that he was an Al Qaeda loyalist, which was probably true at that point. He denied that he was connected to the September 11 plot, which was also probably true. Maybe Awlaki gamed the bureau, but more likely his radicalization came later than anyone speculated.

The first Al Qaeda–like language wouldn't appear on Awlaki's now-defunct blog until 2009: "I pray that Allah destroys America and all its allies. And the day that happens, and I assure you it will and sooner than you think, I will be very pleased." This was a year and a half after Awlaki was in prison, where he passed as a quiet preacher. He was released from jail in late 2007 and, according to his father, disappeared into lawless Yemen eight months later.

···

There are mountains, there are deserts, and then there is the rare place made of both: That is Yemen. The ruggedness never stops. In the north are the high peaks of the Arabian Shield, and moving south you come, as I did in March, to the Jabal Haraz, a grim range of mountains where biblical-looking men tote AK-47's in the street markets. To the east, the mountains fade out slowly, leaving a series of titanic wadis, or dry river valleys, like Wadi Doan, the poor valley that Osama bin Laden's father left for the riches of Saudi Arabia around 1930. Where the mountains end, there is the Empty Quarter—the harshest desert in the region. I flew over Yemen's south, getting a feel for how it must look through the lens of a drone: an impossible frieze of cracked-stone ridges, rippling black mountains, and brown, waterless deserts, often roadless and obscured by dust storms.

Even the capital of Yemen, the medieval wonder of Sanaa, is located at 7,000 feet. When I was there a few months ago, I found the city center filled with democratically minded young protesters eager for their own version of the Arab Spring. "We want reforms, salary increases, an economy with prosperity, better education, better higher education, and security and stability," a young farmer said. Awlaki and his colleagues claimed a return to an Islamic emirate was coming. And President Ali Abdullah Saleh exploited this specter—après moi le déluge—to neutralize American criticism and remain in power, infuriating the demonstrators, who insist Saleh is the real cause of chaos. The farmer told me he'd had enough of authoritarian leaders dictating loyalties. "No more vendettas," he said.

But Yemen is still an autocracy. To prevent my going back to interview more protesters, Yemen's security apparatus attached a minder to me. A few days after that, I was stopped in Sanaa by agents of the National Security Council, who confiscated my passport. After fourteen hours of harmless detention, I was put on the next flight out of the country.