Last December, about 2,000 armed men met at a village near here called Mergha Khel. The gathering was so large that US forces called for helicopter air support and sent representatives to investigate.
Fortunately, the Afghan men - all members of the powerful Mangal tribe of Pashtuns - told US forces they were plotting how to support the Afghan government, not overthrow it. Their goal, they said, was to maintain law and order out in the rural areas, where more than 80 percent of Afghans live, something that neither the American coalition forces nor the government of President Hamid Karzai were able to do. So the Mangal tribes had decided to form a militia of their own to keep the peace.
"We are happy the Taliban are gone; we have no choice but to be happy," says Haji Mohmand, the Mangal elder who organized the council at Mergha Khel. "But the problem today is that our areas are not safe. If you rebuild a school, but it's not safe, then the children can't go and what's the use of the school? If you build a road, but there is no security, then what's the use of the road?"
The growing assertiveness of tribes like the Mangals could have dramatic repercussions for an Afghan government that has had difficulty extending its authority beyond the capital, Kabul. Not only might these tribes bring back an ancient vigilante style of justice - burning the homes of accused criminals, for instance - but tribal militias could become an obstacle for US forces as they search the countryside for Al Qaeda.
Rival tribes warn that the Mangals could easily switch sides and give their armed support to Al Qaeda if they felt that Kabul was not sufficiently representing Mangal interests. This is not an idle concern. Mangal tribesmen were among the Taliban's most enthusiastic supporters in southeastern Afghanistan.
For now, central and state government officials say they welcome the help of tribes in patrolling the outlying villages. Indeed, Mr. Karzai has been holding regular meetings with tribal elders and gave specific permission for them to form militias, or arbakis, as they are called in the Pashtu language.
"We need their help, their cooperation. If they don't help us, we can't proceed to govern," says Abdullah Khan, deputy governor of the province of Paktia.
In the Gardez area, 60 miles south of Kabul, the Mangal arbaki contains some 500 men, armed with Kalashnikov rifles and answering only to the orders of the spingiris, literally, the whitebeards or elders.
The biggest whitebeard of them all is Shareh Mangal, a burly, compact man who gets his name from wearing an elaborate beaded cloak of many colors, called a shareh.
"We are trying to persuade the other tribes to join us in bringing security to our areas," says Mr. Mangal. "The government is not able to bring security.... So we will give our arbakis to the government to bring the peace."
But whitebeards from other tribes say it's difficult to know the motives of the Mangal tribe, and that the US may be cozying up to the Mangals too quickly.
"The US forces have modern weapons, modern forces, but there are some things you can't do in a fast, modern way, and choosing your friends is one of them," says Wakil Sherkhan, an elder in the Tanai tribe, which resides in both Paktia and Khost provinces.
"One hears rumors all the time, but I think it is possible for these arbakis to take action against the central government, and even against US forces," Mr. Sherkhan adds, "because money makes everything possible. If someone gives you 100 Afghanis [Afghan currency] and I gave you 2,000, who are you going to favor?"
Bismillah Khan, a young Mangal arbaki fighter from the village of Jane Khel, says he has sworn allegiance to the government in Kabul. "We took an oath on the Koran to support the central government, and as a Muslim we must obey that oath," says Mr. Khan. "But we also took an oath in our hearts to show that we are a real power, a real force."
While the common people of the Mangal tribe complain just as bitterly about US forces searching their homes as they do about thieves on the road, Khan says that the Mangal arbaki would not take revenge against US troops.
"It depends on the US forces and what they do," he says, "but we are not more powerful than the US forces, so if we don't have the power to do anything by force, we will solve the problem peacefully."