ISLAMABAD, Pakistan — Islamic militants known as the Pakistani Taliban have extended their reach across all seven of Pakistan's frontier tribal regions and have infiltrated Peshawar, the provincial capital, heightening U.S. concerns that an insurrection may be broadening in the nuclear-armed nation.
Fighting over the weekend spilled into previously peaceful parts of the tribal belt that borders Afghanistan and intensified in South Waziristan, Bajour and Mohmand. In Bannu, southwest of Peshawar, gunmen fleeing police took dozens of schoolchildren hostage for several hours Monday before tribal elders brokered a deal offering them safe passage, state-run television reported.
"It's worsening day by day," said Safraz Khan, a political scientist at the University of Peshawar. "People feel vulnerable. People feel scared."
A disparate group of tribal armed militant groups, some of them linked to al Qaida, announced the formation of an alliance last month called The Taliban Movement of Pakistan. The 40-man leadership is from seven tribal agencies and eight bordering districts, underscoring the movement's reach. The group is thought to have 5,000 to 10,000 fighters and is growing steadily as it gains momentum.
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U.S. officials are deeply concerned that the insurgency is becoming bolder and expanding faster than had been anticipated, a State Department official said.
"The feeling is that we are not dealing with a terrorist group here, but an insurrectionist movement," said the official, who spoke on the condition of anonymity because of the sensitivity of the issue. "That's an elevation without question from what we've been dealing with."
He noted the broad scale of fighting across the tribal agencies, which together form the Federally Administered Tribal Areas, and in settled parts to the east.
"These are not groups of Pashtun brigands popping potshots at army patrols," he said. "This looks like there is clearly coordination going on. This looks like an effort that appears to have been planned."
Some U.S. officials think that al Qaida is providing the coordination, but others say it's too early to reach that conclusion, he said.
Traffic finally returned to normal Monday along the key Indus Highway, which connects Peshawar to the port of Karachi, after soldiers backed by helicopter gunships regained control of a 1.2-mile-long tunnel that militants had captured late last week while seizing four army ammunition trucks.
Skirmishes around the Kohat Tunnel and in Darra Adamkhel, 25 miles south of Peshawar, heightened the sense that Peshawar, the garrison city of 2 million residents, faces peril from the spreading violence.
The increased fighting also has U.S. officials worried about possible threats to supply lines to U.S.-led NATO forces in Afghanistan, which stretch from Karachi through the tribal territories, the State Department official said.
The State Department official also said that there were indications of a flow into Pakistan of fighters from Afghanistan who apparently sensed that there was "an opportunity to achieve a significant victory in Pakistan."
Momentum by the Pakistani Taliban has thrown President Pervez Musharraf on the defensive over the army's ability to fight radicalization of his country.
"We haven't failed," Musharraf said Monday, bristling in response to a question in London, where he was traveling. "We are going around fighting al Qaida, fighting the Taliban . . . and fighting extremism in some parts of Pakistan society."
Mahmood Shah, a retired brigadier general based in Peshawar, said government forces had been "sleeping" as the militants strengthened, gaining new adherents.
"As they become more successful, many criminals also join them," Shah said. "They grow beards and they become 'pure.' "
Shah said he hoped that Gen. Ashfaq Parvez Kayani, the recently installed army chief, and the army's vigorous engagement of militants in South Waziristan, the most conflictive tribal agency, would signal more concerted action.
But senior army officers are clearly uneasy about fighting fellow Pakistanis.
"These people are not our enemies. ... These people have been misguided," army spokesman Maj. Gen. Athar Abbas said in an interview.
In many tribal areas, Taliban militants establish checkpoints, collect fees, shut down or blow up video stores with racy films, hector women to wear veils and order wives to ride only in the back seats of vehicles.
Such radical influence now is seeping into Peshawar, especially at the university.
"They say I should have a beard and my hair down to here," said Khan, the political scientist, putting his hand at shoulder level. "They want me to be praying five times a day. They want me not to watch television."
Khan, whose family has fled the embattled Swat Valley, north of Peshawar, said he feared that radicals entering the university might take his life.
"I almost don't go anywhere now, just to my office and my home," he said.
A few weeks ago, Taliban sympathizers briefly set up a booth at the school to collect money. The group is illegal, but police didn't stop them.
"People are afraid to confront them," said Ijaz Khan, another scholar at the university.
Although rockets occasionally rain down on Peshawar — there were 11 on Jan. 6 and another Saturday on Hayatabad, a prosperous residential area — some analysts don't think the city will come under direct siege.
"I don't think the Taliban, at this stage, have any plans to capture Peshawar," said Rahimullah Yusufzai, the editor of the Peshawar bureau of The News, a national daily newspaper.
He said the Taliban actions over a broader area were intended to take heat off South Waziristan, where soldiers have used helicopter-borne aerial bombardments and long-range artillery. Mountainous South Waziristan is the base of Baitullah Mehsud, the leader of the Pakistani Taliban.
"The militants are trying to put pressure on the Pakistani army so the military campaign in Waziristan is either called off or the attention is diverted," Yusufzai said.
(Landay reported from Washington.)