In 2009 and 2010, Mr. Awlaki seems to have been mostly in the southern heartland of his own powerful tribe, the Awaliq, where killing him would have been politically costly for the government, and capturing him nearly impossible. The area where Mr. Awlaki was finally killed, in the remote north, did not afford him the same tribal protection. There are also many tribal leaders in the far north who receive stipends from Saudi Arabia — the terrorist group’s chief target — and who would therefore have had more motive to assist in killing him.

The hunt for Mr. Awlaki has involved some close calls, including the failed American drone strike in May, and the previously unreported operation in the Yemeni village. Yemen’s elite counterterrorism commandos, backed by weapons from Yemen’s regular armed forces, formed a ring around the town as commanders began negotiating with local leaders to hand Mr. Awlaki over, said one member of the unit.

“We stayed a whole week, but the villagers were supporting him,” said the counterterrorism officer, who is not authorized to speak on the record. “The local people began firing on us, and we fired back, and while it was happening, they helped him to escape.”…

A senior American military official who monitors Yemen closely said Mr. Awlaki’s death would send an important message to the surviving leaders and foot soldiers in the Qaeda affiliate. “It’s critically important,” the senior official said. “It sets a sense of doom for the rest of them. Getting Awlaki, given his tight operational security, increases the sense of fear. It’s hard for them to attack when they’re trying to protect their own back side.”