“Some of what looks like Al Qaeda is really terror as a business,” Mr. Faqih said.

Yemen’s tribes are often cast as the chief obstacle in the fight against Al Qaeda, sheltering the militants because of tribal hospitality or even ideological kinship. In fact, few tribal leaders have any sympathy for the group, and some tribes have forced Qaeda members to leave their areas in the past year.

In a statement released Tuesday, a group identifying itself as Al Qaeda members from the Awlaq tribe  one of Yemen’s largest  pleaded with their fellow tribesmen for support, noting that “we were deeply saddened to see the leaders, chiefs, and dignitaries of our community go personally to meet with the government envoy.”

Instead, Al Qaeda seems to thrive where tribal authority has eroded, or in the southern areas where hatred of the government is most intense. In many of the recent attacks, it is difficult to draw a line between Al Qaeda and angry, impoverished young men who have easy access to weapons.

This is particularly true of the secessionist movement in the south. “There are many unemployed young men and people with personal interests who rebelled against the state and against the movement itself,” said Saleh al-Hanashi, an adviser to the governor of Abyan, a southern province where the protest movement thrives and many of the recent killings have taken place. “They became these chaos-inciting groups. And these groups now in Abyan shoot at cars belonging to the state and do other destructive acts against the state.” This kind of vandalism is easily attributed to Al Qaeda, whether the group claims responsibility for it or not. The latest issue of the group’s English-language magazine, Inspire, features a banner headline on the front cover: “Photos From the Operations of Abyan.” Inside, there are gruesome pictures of burning Jeeps and dead Yemeni soldiers.

Many southerners view Mr. Saleh’s government as an occupying force, and while the secessionist movement’s leaders say they reject violence, some of its members may be willing to make common cause with jihadists. North and south Yemen, once separate countries, unified in 1990, then fought a bitter civil war four years later. Many in the south say they have been treated unequally ever since.

It is possible that the worsening carnage in southern Yemen, and Al Qaeda’s claims of responsibility for it, will eventually lead to a shift in perceptions and broader support for the government’s agenda. That is what happened in Saudi Arabia, where attitudes toward Al Qaeda were similar to those in Yemen until the group began carrying out bloody attacks in Saudi cities in 2003. Public opinion soon swung sharply against the jihadists, and by 2006 the Saudis had crushed the group.