The officials said the bomber was a Jordanian doctor likely affiliated and working with al Qaeda.

The Afghan security official identified the bomber as Hammam Khalil Abu Mallal al-Balawi, who is also known as Abu Dujana al-Khurasani. The Pakistani Taliban also claimed that Mr. al-Balawi was the bomber, Arabic-language Web sites reported Monday.

Mr. al-Balawi was brought to the CIA’s base in Khost Province by the Jordanian intelligence official, Sharif Ali bin Zeid, who was working with the CIA, according to the Afghan security official.

The bomber appears to have been invited to an operational planning meeting on al Qaeda, a former senior U.S. intelligence official said. “It looks like an al Qaeda double agent,” the former official said. “It’s very sophisticated for a terrorist group that’s supposedly on the run.”

The blast on Dec. 30 killed four CIA officers, including the Khost base chief; three CIA contractors; and Mr. bin Zeid, officials said. Six CIA employees were wounded in the attack.

The Al Jazeera television network reported that the bomber had initially been recruited to provide intelligence on the whereabouts of Osama bin Laden’s top deputy, Ayman al Zawahiri. That couldn’t be independently confirmed Monday.

The CIA’s deputy chief of station from Kabul traveled to the meeting at the CIA Khost base, Forward Operating Base Chapman, according to former intelligence officials, pointing to the meeting’s importance. The officer was wounded in the attack, according to people familiar with the matter.

Both the Pakistani Taliban and the Afghan Taliban have claimed responsibility for the attack. The Afghan Taliban fights alongside an array of allied militants including the Haqqani network, an Islamic extremist group that operates in Afghanistan and Pakistan and maintains close ties to al Qaeda.

The U.S. and Jordanian intelligence services have worked closely together for years, said a former senior intelligence official. “There’s a confidence level with them,” the former official said. Mr. al-Balawi likely was seen as trustworthy because he’d previously provided the U.S. with valuable intelligence, said the former intelligence official. “This is someone they obviously trusted very, very much,” the former official said.

Since Mr. al-Balawi was perceived by U.S. authorities as a cooperative intelligence informant, that could explain why he was not more thoroughly searched upon entering Chapman. It also would explain how he gained access to top intelligence officials.

Mr. al-Balawi was an active recruiter and an “elite writer” on al Qaeda’s password-protected al-Hisba Web site, where he went by the name Abu Dujana al-Khurasani, according to the monthly journal of the U.S. Military Academy at West Point’s Combating Terrorism Center.

In a posting on the site in May of 2007, Mr. al-Balawi sought to persuade people from a variety of backgrounds, including African-Americans, Native Americans, Vietnamese and poor immigrants to join the fight against their “oppressor,” the U.S., the West Point analysts found.

Mr. al-Balawi had studied medicine in Turkey with government funding, according to a translation of the Jordanian Web site Jerasa News by the Middle East Media Research Institute. He left Jordan about a year ago after being detained for a few months by Jordanian intelligence officers.

The Jordanian news outlet cited eyewitness reports that Jordanian security forces had arrested Mr. al-Balawi’s youngest brother and summoned his father after the blast. They warned his father not to put up a mourning tent, fearing it could attract jihadis, the news outlet said.

Senior U.S. military officials believe that the Khost attack was carried out with the active assistance of the Haqqani network, which has mounted dozens of bloody attacks inside Khost that have turned the province into one of the most violent regions of Afghanistan.

U.S. policy makers worry that any territory that falls under Haqqani control in either Afghanistan or Pakistan could quickly become a new safe haven for al Qaeda, whose senior leaders have known and fought alongside the Haqqani family for decades. The CIA and elite U.S. Special Operations troops have responded to the Haqqani group’s offensive in Khost with a stepped-up campaign targeting the militants, and senior officials say more than two dozen Haqqani officials have been killed in recent weeks.

While coordination between the Haqqani network and the Pakistani Taliban is rare, members of both groups have said that they cooperated in the past. “At times they send suicide attackers to our area, and we give them shelter and find targets for them,” said a former Haqqani commander in an interview this summer. The commander has since left the group and made peace with the Afghan government.

A U.S. intelligence official declined to speak about the specifics of the attack but said the agency “is looking closely at every aspect of the Khost attack.” The official added, “The agency is determined to continue pursuing aggressive counterterrorism operations. Last week’s attack will be avenged.”

A former senior intelligence official said that al Qaeda had attempted to run double agents against the CIA prior to 9/11, but such efforts appeared to trail off after the 2001 offensive in Afghanistan that drove them into the tribal regions of Pakistan.

The bodies of the seven CIA employees arrived in the U.S. Monday, and CIA Director Leon Panetta, along with other agency officials and family members, attended a private ceremony at Dover Air Force Base to honor them, said CIA spokesman George Little.
—James Oberman contributed to this article.

KABUL–The Taliban said in a statement Saturday it would provide a “legal guarantee” that they would not intervene in foreign countries if international troops withdraw from Afghanistan, the closest the movement has come to publicly distancing itself from Al Qaeda.

The Taliban have “no agenda of meddling in the internal affairs of other countries and is ready to give legal guarantee if the foreign forces withdraw from Afghanistan,” the group said in a statement emailed to news organizations.

The statement did not specify what such a guarantee would look like. A Taliban spokesman was not available for comment.

U.S. President Barack Obama has said that the main purpose of the war here is to prevent al Qaeda from reacquiring a safe haven from which its member can launch attacks against the West. U.S. and Afghan officials have been looking for ways to exploit the differences between al Qaeda, a mostly Arab organization that is focused on fighting a global holy war, and the Taliban, an Afghan group that largely restricts its activities to Afghanistan though it has links to the Taliban in neighboring Pakistan.

U.S. officials are skeptical that the Taliban can be taken at their word. “This is the same group that refused to give up (Osama) Bin Laden, even though they could have saved their country from war,” said a U.S. official. “They wouldn’t break with terrorists then, so why would we take them seriously now?”

In the years immediately following the U.S. invasion, Taliban leader Mullah Omar repeatedly pledged his support for Mr. bin Laden. But in recent times the movement has fallen silent on the question of al Qaeda, with most of its communiqués repeatedly emphasizing the group’s willingness to engage with the international community. In an October message, for instance, they attempted to reach out to the Shanghai Cooperation Organization, a mutual security organization comprising Russia, China and some Central Asian states.

Such moves caused a flurry of dissent from al Qaeda-linked militants, who posted sharply critical statements on a number of Islamic-extremist Web sites. Al Qaeda has declared a global jihad and rejects any collaboration with what it views as enemy governments.

Nonetheless, U.S. officials said that there is not enough evidence that these tensions exist at the leadership levels of al Qaeda and the Taliban. “If the Taliban really want to break with al Qaeda, they should say so openly and denounce terrorism,” said the U.S. official. “Otherwise there is no reason we should trust them on anything.”

President Barack Obama has been briefing allies about his plans for Afghanistan. He’s expected to tell the public — and lawmakers — how many more troops he’ll send and that it’s not an open-ended commitment. Video courtesy of Fox News.

“We should focus on building the Afghan security forces, not sending more troops,” said Sebgatullah Sanjar, the chief policy adviser to Afghan President Hamid Karzai.

The U.S. and its allies hope that by sending more troops they can push the Taliban back from areas where they have been operating freely for years, and impede the insurgents’ ability to operate. This would create the space needed to bring development and begin to win over a war-weary population.

A minority in the Afghan government, such as the interior minister and certain leading officials in the country’s security forces, has spoken publicly in favor of the increase. Moreover, many residents of peaceful non-Pashtun areas of the country say they welcome a troop increase as a way to keep insurgents at bay.

But several senior Afghan officials said the U.S. should deploy troops only to the porous border with Pakistan and not the country’s interior. Mr. Karzai has said publicly that he welcomes more troops, but close aides said he hoped the troops would go to the border.

Many tribal heads and local leaders from the Pashtun south and east — the heartland of the Taliban insurgency — have gone further, calling for troop withdrawals. “I don’t think we will be able to solve our problems with military force,” said Muhammad Qasim, a tribal elder from the southern province of Kandahar. “We can solve them by providing jobs and development and by using local leaders to negotiate with the Taliban.”

Such views could pose a challenge to the U.S., which would require the support of the Pashtun population in order to succeed. “People are starting to view the Americans as occupiers, and in that context more troops would be risky,” said Hanif Shah Hosseini, a lawmaker from Khost province.

Officials cite night raids, civilian casualties and lack of development as reasons why the standing of U.S. troops has lowered in some Afghans’ eyes. When the U.S. forces enter an area, the levels of violence generally increase, causing anger and dissatisfaction among the local population. Some officials point to previous troop increases, such as an injection of 21,000 troops in the spring, and say they have failed to quell the insurgency.

“If new troops come and are stationed in civilian areas, when they draw Taliban attacks civilians will end up being killed,” said Gulbadshah Majidi, a lawmaker and close associate of Mr. Karzai. “This will only increase the distance between Afghans and their government.”

In the volatile southern city of Kandahar, where many of the new troops are expected to head, locals said they will be glued to their radio sets on Wednesday morning to hear news of Mr. Obama’s new strategy.

“If we get more troops, there will be more bloodshed,” said Noor Muhammad, a shopkeeper. “Only Afghans themselves can solve this problem.”

U.S. authorities contend that Afghan government officials who disapprove of the troop increase are apportioning blame to deflect attention from their own shortcomings. “It’s poor governance more than anything else that has put us in this situation,” said a Kabul-based U.S. official.

U.S. authorities said that they are working to minimize civilian casualties and that a military thrust to push back the Taliban is necessary to bring needed political and economic change.

Moreover, they say that the alternative espoused by opponents to the troop increase — concentration on the development of the Afghan forces — is premature. “It could take some years before the Afghan security forces are able to stand on their own,” said Capt. Bill Spurlock, who is involved in overseeing the training of Afghan army recruits.

The Afghan army has made many strides, but is plagued by lack of experience and illiteracy. The Afghan police force is even less capable and is widely accused of corruption and inefficiency. On Sunday, a police officer opened fire on his comrades, killing six and wounding two. The incident came less than a month after a police officer killed five British soldiers in a similar attack.

U.S. funding and support will be needed for a significant expansion of Afghan security forces. Officials in Washington said an expansion of Afghan forces is unlikely until the government and security sector improve. A U.S. troop increase could provide the space and support needed for the Afghan forces to develop, U.S. officials said.
—Habib Zahori contributed to this article.

While President Hamid Karzai’s government has been trying to woo these insurgents for years, the new program marks the first time that the U.S.-led North Atlantic Treaty Organization forces are systematically reaching out to Taliban fighters.

The tactic comes as the U.S. prepares to announce Tuesday how many additional troops it will send to Afghanistan as part of a new strategy aimed at bringing the eight-year war to a successful end. U.S. officials also hope America’s European allies will raise their troop contributions as part of the new push.

The Afghan government has had a reconciliation program in place since 2004, and claims to have turned more than 8,000 insurgents. That program, however, is widely derided as corrupt and ineffective. Insurgents were enticed with offers of jobs but rarely received the promised assistance, leading many to rejoin the fight.

Western officials behind the new reconciliation program say they believe the majority of insurgents are fighting for money — the Taliban often pay their members — or personal grievances. Luring such men from the battlefield is a central component of America’s new counterinsurgency strategy crafted by U.S. Gen. Stanley McChrystal, the top allied commander here.

“It is an issue of dialogue — we need to establish respect, even if they are the enemy,” said Graeme Lamb, a retired British general who spearheaded a similar effort to turn Sunni insurgents in Iraq, and who oversees the campaign out of NATO headquarters in Kabul.

The Iraqi program split local Sunni insurgents from al Qaeda’s foreign fighters in the tribal Anbar province, recruiting many of them into paramilitary forces. It is widely credited with driving down the level of violence there, eventually allowing the U.S. to begin drawing down its forces.

President Barack Obama signed a bill in October that earmarks funds to pay former Taliban members to protect Afghan towns and villages from insurgents.

The Afghan government and coalition military officials have already begun using tribal elders and other influential figures to reach out to the Taliban in the south’s restive Helmand province. The elders negotiate on behalf of the government, and insurgents are offered jobs with the local police force. Helmand Gov. Gulab Mangal said if necessary, the authorities will pay cash to those willing to lay down arms.

“It has to be a local solution, specific to each community,” Mr. Lamb said. “If you try to control everything from Kabul, you will be doomed.”

The Taliban’s senior leadership met the new reconciliation efforts with scorn. The Islamist movement is “considering this decision as a sign of weakness and complete despondency of the enemy,” Mullah Brader Akhund, the Afghan Taliban’s second-in-command, said in a statement posted on jihadi Web sites. The insurgents, he added, “have not chosen this path of strife between the truth and the evil to obtain some material goals.”

Gul Wazir, a midlevel Taliban commander who fought the Americans for nearly eight years south of Kabul, has been disappointed with the Afghan central government’s current reconciliation program. When Mr. Wazir, a middle-age man with a thick, wiry beard and a row of silver teeth, decided to stop fighting in September, the government promised to protect him from his erstwhile comrades, who were threatening to kill him for defecting. It also promised a job, he says.

But no job or protection materialized, and Mr. Wazir says he was forced to flee for the relative safety of Kabul, where he spends his days looking for work. “The government hasn’t done a single thing for me,” he complains. “I am jobless and my life was better when I was fighting.”

Mr. Wazir’s predicament is common — and the current reconciliation program’s failures are further inflaming the insurgency, analysts say. “Thousands of insurgents come and renounce violence, get a card from the government, and then go back and continue fighting,” said Rafiullah Bidar, a senior official of the Afghan Independent Human Rights Commission.

Afghan officials said they plan to revamp the existing reconciliation program and, together with NATO forces, create a new body that supervises the process. The new job and literacy-training programs, Mr. Lamb explained, would help ensure that reformed fighters are not “left in the cold.”

It is far from certain that the new program will produce better results, analysts say, at least as long as the Taliban retain momentum in the battlefield.

KABUL — The collapse of security in the southeastern Afghan province of Khost is highlighting the difficulties of trying to contain the Taliban.

In 2007 and early 2008, troops from the Army’s 82nd Airborne Division waged a long, bloody and seemingly successful campaign to push Taliban fighters and their allies from the Haqqani terrorist network out of Khost. Diplomat Richard Holbrooke, now President Barack Obama’s special envoy to the region, wrote an op-ed calling it “an American success story.”

Today, Khost is one of the most dangerous provinces in Afghanistan. Afghan officials say the number of militant attacks in the province is up at least 31% so far this year.

In early May, teams of suicide bombers killed more than 20 people in Khost city, the provincial capital. In July, heavily armed insurgents disguised in head-to-toe coverings typically worn by women slipped into the city and attacked government installations.

Gen. Stanley McChrystal, the top U.S. commander in Afghanistan, wrote that regaining control of Khost was the insurgents’ second-biggest goal in the country, after capturing the city of Kandahar, the Taliban’s spiritual birthplace.

The situation in Khost has given the Taliban space to solidify their alliance with the Haqqani network, an extremist group that has become the Taliban’s most important battlefield partner in the war against the U.S. The network maintains close ties to the al Qaeda leadership in Pakistan. U.S. officials fear a Haqqani-controlled Khost would quickly become a new haven for al Qaeda in Afghanistan.

Sirajuddin Haqqani, the network’s leader, said in a rare phone interview that his fighters were working to expand their influence. “Outside of the district centers everything is controlled by our mujahedeen. … The foreign and Afghan forces hardly ever leave their bases and come to the villages,” he said.

Afghan elected officials from Khost agree that the Haqqani group controls much of the province. Col. Wayne Shanks, a U.S. military spokesman, declined to comment on operations in the area.

“Khost is in a lot of ways a microcosm for what’s happening in Afghanistan,” said Andrew Exum, a counterinsurgency expert in Washington who advises Gen. McChrystal. “A resurgent insurgent group has become more aggressive as U.S. troop levels have remained too low to really protect the population.”

A military official said the U.S. now had roughly 2,400 troops in the province, about double what had been there in previous years. A defense official involved in the current administration debate said he thought the U.S. should ideally deploy at least 1,000 or 2,000 more troops there.

Most violence in the province has been linked to the Haqqani network, which operates out of havens on both sides of the porous Afghanistan-Pakistan border and has taken responsibility for dozens of attacks around Afghanistan.

The group was founded by Jalaluddin Haqqani, who made his name as a leader of the Islamist uprising against the Soviet occupation in the 1980s. More recently, the militants introduced the use of suicide bombings to Afghanistan.

Sirajuddin Haqqani, Jalaluddin’s son, said his fighters didn’t want to capture heavily populated areas because the operations would likely result in significant casualties among insurgents and civilians. Still, he made clear his group had no intention of abandoning its focus on Khost. “Every now and then we want to carry out coordinated group attacks,” he said.

An American military official who recently served in eastern Afghanistan said the U.S. had intercepted communications suggesting the Haqqani leadership was closely coordinating its activities in Khost with Mullah Omar, the Taliban’s leader, who is believed to be in Pakistan. “It’s a division of labor, with each group focusing on a different part of Afghanistan,” the official said.

The official said some U.S. intelligence officers suspect that the Haqqani leadership had offered to conquer Khost in exchange for a promise from Mullah Omar that the family would be allowed to rule large swaths of eastern Afghanistan if the armed group eventually retook control of the country.

Afghan officials said insurgents now control many of the districts surrounding Khost city and use them as launching pads for attacks targeting the city and for campaigns designed to intimidate the local population there.

The district of Sabari, north of the city, has long been an insurgent stronghold, and another neighboring district called Musa Khel has recently fallen to insurgents, according to Afghan government officials.

Likewise, government control of three other nearby districts is limited to the district capitals, while the surrounding areas are in the hands of the insurgents.

“No Afghan security forces or government employees can travel in these areas,” said Hanif Shah Hosseini, a parliamentarian from Khost. “The insurgents have a shadow government in all of these areas.”

To combat the threat, Afghan officials are planning to boost the number of security forces around Khost city and near the border, and to organize the “arbakai,” the tribal militias charged with guarding local towns and villages.

“We’ve been able to deploy more border police and Afghan army soldiers than ever before, and we plan to continue to increase the numbers,” said provincial Gov. Hamidullah Qalandari.

Still, it may be too late to prevent insurgents from winning the support of local Afghans, officials say.

“At the beginning everyone supported the Americans,” said Mr. Hosseini, the parliamentarian. “But now a lot of locals don’t believe in a U.S. or government victory anymore. They expect the Americans to leave, so they are casting their support to the Taliban.”

KABUL — President Hamid Karzai failed to win a decisive majority in Afghanistan’s election, an official familiar with the ballot counting said, a development that has the two top candidates stepping up power-sharing talks to avoid a protracted runoff.

Results of an audit of suspect votes from the August polls are expected Saturday, Afghan authorities said. Investigators at the U.N.-backed Afghan Electoral Complaints Commission are expected to discard enough votes as fraudulent to trigger a runoff between Mr. Karzai and lead challenger Abdullah Abdullah in coming weeks.

According to Afghan and Western officials in Kabul, Mr. Karzai and Dr. Abdullah are exploring a deal to end the country’s political crisis by forgoing a second round and crafting a power-sharing arrangement.

The deal likely wouldn’t create a position for Dr. Abdullah, officials said, but could require Mr. Karzai to give key cabinet posts and governorships to members of Dr. Abdullah’s team.

Representatives from the Karzai and Abdullah camps deny making any deals, although both sides have said they are open to the notion in principle. Both sides are loath to engage in a runoff, which could be hobbled by low turnout, security risks and fraud. Officials with knowledge of the talks said it could take more than a week to reach an agreement.

“There is huge international pressure to accept the deal,” said one Western election observer familiar with the process. “They see this as a possible way out of a very difficult situation.”

Negotiations have intensified as the ECC prepares to deliver the results of its audit. The ECC is “triple-checking” its numbers, the official familiar with the audit said, before delivering them to Afghanistan’s Independent Election Commission. The IEC conducted the polls and is widely accused of being biased in favor of Mr. Karzai.

The ECC review focused on three categories, the official said: Results from polling stations that the commission deemed had suspect ballots, complaints of fraud by individuals, and complaints referred by the IEC.

After the ECC audit of suspect polling-station results, Mr. Abdullah had 31% of the vote and Mr. Karzai 48% — shy of the majority required to avoid a runoff, the official said. When the ECC factors in results from its audit of complaints by individuals and the IEC, Mr. Karzai’s lead could fall to between 46% and 48%, the official said.

“Ballot box after ballot box was full of obviously fraudulent votes,” said another official who observed the audit process. “The majority of these were in favor of Karzai. If these are thrown out we are likely to be in the 47 to 49% range,” he added, referring to Mr. Karzai’s likely vote total after the audit.

A runoff could help defuse a political crisis that has dented the Afghan government’s credibility and prompted Washington to review its Afghanistan strategy. But it could also prolong the uncertainty in the country at a time when American death tolls are mounting and the Taliban’s reach is expanding. Election officials most likely won’t be ready for another round of voting until at least November, and the subsequent vote tally and certification could last well into January, officials said.

White House officials said Afghanistan’s electoral uncertainty has had an effect on their deliberations over war strategy, an acknowledgement that could mean further delays in a final decision by President Barack Obama on whether to send tens of thousands of additional troops to the country.

Secretary of State Hillary Clinton said that, while the U.S. is awaiting word of whether a runoff would be ordered, the likelihood of Mr. Karzai winning a second round “is probably pretty high.”

In an interview with CNN, Mrs. Clinton said if Mr. Karzai emerges victorious, the U.S. would likely push for “measures of accountability” on his government aimed at curbing corruption.

– Peter Siegel contributed to this article.

KHAS KUNAR, Afghanistan — U.S. and Pakistani troops recently planned a pincer movement to catch insurgents crossing the border from Pakistan into this troubled corner of northeastern Afghanistan. The U.S. would block the narrow mountain passes while the Pakistani army attacked militant positions on the other side of the border.

The operation failed. The reason, according to the Americans: Their partners in the Afghan Border Police had informed the insurgents, allowing them to slip away.

“Every time we tried it, there was a leak,” says Lt. Ryan Keogh, a company commander who helped to plan and execute the operations. “If we can’t rely on the Afghans in this fight, then we are going to be here for a long time.”

Counting on Afghanistan’s security forces to help stabilize the nation is seen as vital if the international force is to turn around a deteriorating security situation.

There are signs the Afghan army is becoming equipped for that task. But U.S. officials say the Afghan police force remains widely corrupt and largely ineffective.

Abdul Hayat Rafi, chief of staff in the Afghan Border Police, denies that any of his men have links to insurgents, but says there may be corruption among the country’s police forces.

A North Atlantic Treaty Organization official in Brussels said Wednesday that NATO is planning to bring more experts to Afghanistan to train the police force. “The police have always lagged behind the army,” said the official. “We have a shortage of trainers, which we hope to fix now.”

Officials also plan to increase the number of mentors who will live with and advise police units in the field. The approach has led to some successes with the Afghan army, the NATO official said.

The police-training initiative, which is set to receive more than $1 billion in funding next year, largely from the U.S., will be headed by an American three-star general and will start in the coming weeks.

The U.S. and its allies have already spent millions of dollars to create the Afghan Border Police, making it the best-funded component of the Afghan security forces. Of Afghanistan’s police force of about 80,000, there are nearly 12,000 border police, and there are plans to expand the force to nearly 18,000.

This year, the U.S. began working with the border police in an intensive training initiative similar to one used elsewhere in the country. In some cases, military trainers live alongside newly trained police for a number of months as mentors.

But many of the border police still haven’t been trained, and some units that have been trained are still compromised because of corruption and ties to local insurgents, U.S. military officials say.

Here in Kunar province, soldiers from the 10th Mountain Division, have been policing the porous 150-mile border, often in partnership with the ABP.

The ABP, however, “is often part of the problem,” said Lt. Gabriel Lamois, a platoon commander. Lt. Lamois said members of the border police have a hand in the illegal timber and gem trades, which fund the insurgency and local warlords, and they often have ties with the insurgents, who control some areas where smuggling occurs.

Border Police commanders say their chief problem is a lack of resources. Low pay can drive police to use their positions to pursue other sources of income.

Afghanistan’s police forces are drawn from the communities in which they serve. This may make it difficult to create a force that is independent of local concerns. “The police have connections with all sides in the community,” says Habibullah Rafeh, a policy analyst at the Kabul Academy of Sciences. “In situations where an area is contested by the Taliban and the Americans, they don’t know who is going to come out on top so they maintain ties with both sides.”

They also lack the protective equipment of the Americans and are often outgunned by the Taliban. “The Americans can call in air support when they are in trouble,” said Mr. Rafi. “We don’t always have that luxury, so we can’t take as many risks.”

More than 2,000 Afghan police have been killed this year across the country, a toll far higher than that of the Afghan army or the U.S. and NATO forces.

Yet in this border region, while insurgents frequently attack the Afghan army and U.S. troops, the border police are rarely bothered — as long as they stay near their posts.

The result is that it is often difficult for the Americans to persuade the Border Police to go to the border. Recently, Lt. Lamois met with his border police counterpart in a spartan, rock-strewn police outpost six miles from the border. It was a quiet, sunny day, and Lt. Lamois had stopped by to ask the Border Police commander to conduct patrols.

“What can I do to help you cut down on the people crossing over the border?” Lt. Lamois asked.

“Well, the people cross the border at night, and we can’t leave our compound at night — it’s too dangerous,” replied Capt. Karim, who goes by one name and commands about 80 Border Police here.

Later in the same discussion, Lt. Lamois asked Capt. Karim what he would do if he had all the resources he needed.

“I would bomb Pakistan,” he replied.

“Well, I don’t think we can do that,” Lt. Lamois said. “What about patrolling the border?”

Capt. Karim thought for a moment. “No,” he said, shaking his head. “It’s too dangerous.”

KABUL — An American airstrike on militants in northern Afghanistan killed an unknown number of local villagers, dealing a fresh blow to the U.S. campaign and adding fresh political pressure on NATO members struggling to defend an increasingly unpopular war.

The strike on a pair of hijacked fuel trucks in Kunduz Province sparked an immediate investigation by U.S and Afghan officials. It underscored the American military’s continuing struggle to prevent civilian deaths, just days after guidelines were issued to troops reminding them of that responsibility.

Two Western military officials acknowledged in interviews that early indications suggested significant numbers of civilians had died in the attack, though the number hasn’t been determined. Afghan officials said that up to 90 people died in the attack, including a large number of villagers who had been trying to siphon away fuel from the stalled trucks.

“We heard an incredibly loud bang and soon I saw body parts everywhere,” said Hajji Tahir, a tribal elder from the village of Omar Khel who witnessed the attack. “A lot of people were burning.”

North Atlantic Treaty Organization officials confirmed the strike, which had been called in by German troops in the area. In a statement, the military alliance said its personnel “observed insurgent activity and assessed civilians were not in the area” before ordering the attack and were confident that the dead mostly included Taliban fighters. Local Afghan tribal leaders and government officials immediately disputed the NATO claims.

A Western defense official in Kabul said that investigators were focusing on what happened around the trucks during the roughly 40 minutes that elapsed between when German forces first requested the strike and when U.S. war planes ultimately bombed the trucks. Villagers who weren’t initially nearby may have surrounded the trucks during that time, leaving them vulnerable to the American strike, he said.

Determining the precise death toll from such strikes has been difficult. Last May, a U.S. B-1 bomber and four F-18 fighters hit targets in western Afghanistan’s Farah Province. The Afghan government maintains that 140 civilians were killed there. After investigating the strikes, the U.S. military said 20 to 30 civilians died, along with up to 65 insurgents.

The Kunduz strike may have violated conditions set by the top American commander in Afghanistan, Gen. Stanley McChrystal, for the use of bombs, missiles and other heavy weaponry in areas where civilians might be present. A NATO official familiar with the investigation into the Kunduz incident said that German troops in the area weren’t being fired on by the Taliban and didn’t appear to be in imminent danger.

“One question is why the Germans requested the strike in the first place, and one question is who authorized it, and why,” the official said. The German embassy in Washington didn’t respond to calls or emails seeking comment. NATO officials in Kabul said they wouldn’t comment until their investigation was complete.

Gen. McChrystal reiterated his guidance on the use of force earlier this week, issuing new guidelines to the U.S. and NATO troops under his command. He warned that foreign forces would inevitably be blamed for any civilian deaths, regardless of who had actually caused them. “If civilians die in a firefight, it does not matter who shot them — we still failed to protect them from harm,” the guidelines said.

The early-morning strike is likely to stoke debate in the run-up to German national elections on Sept. 27. Polls have consistently shown that a majority of Germans are opposed to Germany’s presence in the NATO mission. There are more than 4,000 German soldiers in Afghanistan, and Chancellor Angela Merkel is under steady pressure to pull those troops out.

Beleaguered U.K. Prime Minister Gordon Brown, his re-election chances fading, on Friday offered a defense of the increasingly unpopular British presence in Afghanistan while calling on other NATO members to shoulder more of the burden. Mr. Brown, addressing a think tank, spoke a day after an aide to his defense minister resigned in protest over Britain’s Afghanistan campaign.

Yet the political impact will be most immediate in the combustible aftermath of Afghanistan’s presidential election.

U.S. officials had hoped that last month’s presidential vote would bring both political and security benefits. But accusations of systematic voter fraud on behalf of embattled Afghan President Hamid Karzai have sparked growing public anger within Afghanistan, while Taliban attacks on polling stations kept many voters away. The results are still being tallied.

The Taliban insurgency, meanwhile, continues to grow in both strength and geographical reach. This year is already the bloodiest to date for foreign forces in Afghanistan. The 51 American troops who were killed in August represented the largest monthly U.S. death toll since the conflict began 2001.

The insurgency had long been concentrated in eastern and southern Afghanistan. But senior U.S. officials now acknowledge that the Islamist fighters have moved beyond their traditional strongholds to threaten formerly stable areas of northern and western Afghanistan, such as Kunduz, the site of Friday’s NATO strike.

With political support for the war falling in the U.S. and most NATO countries, a number of commentators and elected officials have called for withdrawing most ground troops from Afghanistan and instead relying mainly air strikes and small numbers of elite special-operations personnel.

“America should do only what can be done from offshore, using intelligence, drones, cruise missiles, airstrikes and small, potent Special Forces units, concentrating on the porous 1,500-mile border with Pakistan, a nation that actually matters,” conservative commentator George Will wrote this week in a widely read Washington Post column.

U.S. military officials reject that approach, arguing that it would be dangerous to regularly call in air strikes without troops on the ground or nearby who could help differentiate between militants and civilians.

“You can’t do it remotely, and you can’t do it offshore,” Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, told reporters Thursday.

A Western military official in Kabul said that the Kunduz incident began late Thursday night, when Taliban fighters hijacked the two large fuel trucks in the vicinity of a German base.

Kunduz had long been relatively stable, but the number of insurgent attacks has doubled compared to last year, according to Afghan intelligence officials. The Taliban operate a shadow government in the area, collecting taxes and sometimes providing alms to poor villagers, according to locals.

The Taliban were driving the trucks through the local insurgent stronghold of Char Dara, possibly for use in a later suicide attack, when the vehicles got stuck on a small bridge, officials and locals said.

The provincial governor, Muhaamad Omar, said that hundreds of villagers from the destitute area gathered around the trucks to siphon off fuel and were caught in the fireball that erupted after the American bombs hit the vehicles

Kunduz provincial officials and locals estimated that a large number of civilians were killed in the attack. Dr. Azizullah Safar, the chairman of the Public Health Department of Kunduz, said 12 civilians were brought to the main hospital in critical condition, and one had died.

Poor roads slowed the transport of wounded to the hospital, and hospital staff were told by villagers to expect more patients, he added.

—Matthew Rosenberg contributed to this article.

Since the Aug. 20 election, Taliban fighters have launched nearly a dozen attacks. They have severed the fingers of voters, stolen ballot boxes, and murdered government officials. Afghan police have been reluctant to move into Taliban-controlled areas to quell the violence.

In Wardak province, west of Kabul, local officials say the insurgents have been setting up checkpoints to look for voters who are easily identifiable by the blue ink marks on their fingertips. In one such incident in Saydabad district, the Taliban killed three voters, according to witnesses. Also in Wardak, insurgents chopped off the fingers of four people who had voted at the provincial capital, according to local tribal elder Maualem Ghulab. Human-rights officials reported a similar attack in Kandahar shortly after the election.

In at least three provinces, insurgents also intercepted convoys carrying ballots and burned the papers, most recently on Wednesday. Election officials say the destroyed ballots represented a minuscule portion of total votes cast.

“Insurgents will use any excuse to try to paint the electoral process into the corner,” said Canadian army Brig. Gen. Eric Tremblay, a spokesman for the North Atlantic Treaty Organization’s Afghanistan task force. “It’s up to the people to reject this.”
Regional Violence

As of Wednesday, election officials said they had counted returns from about 17% of Afghanistan’s 24,367 polling stations. President Hamid Karzai’s lead widened from the first day’s announced results, with 42.3% of the vote for Mr. Karzai, 33.1% for former Foreign Minister Abdullah Abdullah, and the remainder split among the nearly three dozen other candidates. The tallies, which are being released gradually over several days, so far make up a sample too small and unrepresentative to project a final tally.

While the Taliban’s attacks have done little to disrupt the vote count so far, they are expected to keep trying. If no candidate gets more than 50% of the vote in the first round of voting, there will be a runoff between the top two candidates, likely in October.

The attacks add to the unstable political situation stirred up in recent days by widespread allegations of vote-rigging. The top two contenders have both declared victory and accused the other of trying to steal the election. Officials haven’t yet released turnout figures for the Aug. 20 vote, leaving it unclear just how effective the Taliban were at keeping Afghans from the polls. Militants launched hundreds of small attacks on Election Day, killing 26 people.

The Taliban also have continued their efforts to destabilize the government. On Wednesday, insurgents killed a high-ranking provincial government official in the northern province of Kunduz and a district governor in Kandahar, the southern province that is the Taliban’s spiritual birthplace.

A day earlier, a truck bomb tore through a crowded section of Kandahar city, killing at least 43 and injuring 65. The Taliban denied responsibility, although they often refrain from taking responsibility for attacks in which large numbers of civilians are killed. The attack was the largest the city had seen in many months, but it wasn’t clear if the blast was related to the election.

Analysts worry the unsettled political climate is providing the Taliban more breathing room to operate and shift into attack mode.

“If the crisis in Kabul continues for some months, it may distract the government and give the Taliban a chance to launch an even stronger offensive,” said Habibullah Rafeh, policy analyst with the Kabul Academy of Sciences.

The absence of any major attack on Election Day prompted the U.S. military and Afghan security forces to declare their efforts to secure the vote a success.

In the week since the vote, the number of Taliban attacks has returned to this summer’s average of about 250 a week, down from more than 500 during election week, according to Sami Kovanen of the security analysis firm Tundra Security in Kabul. Insurgent activity typically tapers off during the Muslim holy month of Ramadan, which started Friday.

A linchpin of the international community’s strategy here, Thursday’s election was supposed to shore up the credibility of the Western-backed Afghan government threatened by a spreading Taliban insurgency. Rolling back Taliban advances and reinvigorating Afghanistan’s development are the key goals of President Barack Obama’s administration, which has poured tens of thousands of additional U.S. troops into the country in recent months.

But now, as rivals of President Hamid Karzai allege widespread ballot-stuffing in his favor, the poll may have produced some unintended consequences. Allegations of fraud could end up eroding Afghanistan’s stability, fracturing the part of the Afghan society that is opposed to the Taliban — and making it even more difficult to contain the insurgency, say those tracking the election.

“The Obama administration’s policy hinges on whether a legitimate leader emerges from this election,” says Brian Katulis, a senior fellow at the Center for American Progress, a Washington-based think tank, who observed the Afghan vote. “Without a legitimate civilian leadership here you’ll have a shaky foundation for the whole policy.”

A partial preliminary vote count is expected Tuesday at the earliest, and it will be weeks before the final result is known.

Both President Karzai and his main rival, former foreign minister Abdullah Abdullah, have staked conflicting claims of victory. Both maintain they have won an absolute majority of votes in an election contested by dozens of candidates.

Afghanistan’s electoral commission, which Dr. Abdullah accuses of siding with the incumbent, President Karzai, says it won’t be able to release partial results before Tuesday. Should any of the candidates fail to win an outright majority, a runoff is supposed to be held sometime in October.

Shortly after Afghan polls closed last week, President Obama hailed “what appears to be a successful election in Afghanistan despite the Taliban’s effort to disrupt it.” However, international observers inside Afghanistan have since provided a much more guarded endorsement, as reports of irregularities have arrived from the field.

The National Democratic Institute, which had more than 100 observers in Afghanistan, has highlighted “serious flaws” and said that only “aspects” of the election were in accordance with democratic principles.

Democracy International, another American observer group, cautioned that it is too early to judge whether the election is credible, and urged Afghanistan’s electoral commission to conduct a “fair and transparent” vote count.

The Free and Fair Elections Foundation of Afghanistan, or FEFA, an independent monitoring group that dispatched nearly 7,000 observers to the polls, has found many instances of ballot-stuffing and of biased election workers across the country, said its director Jandad Spingar.

“Any attempts to deny the full extent of the flaws in this election would only serve to further disenfranchise the Afghan electorate,” cautioned Rachel Reid, the Afghanistan-based researcher for Human Rights Watch.

Senior U.S. officials acknowledge that conspiracy theories are already swirling through the country. “There are always rumors in Afghanistan,” Richard Holbrooke, the U.S. special representative for Afghanistan and Pakistan, said over the weekend in the Afghan city of Herat. “We’ve had disputed elections in the United States, and there may be some questions here. That wouldn’t surprise me at all.”

The criticism is prompting a bout of soul-searching among Western officials whose governments provide the indispensable military and financial backing to President Karzai’s administration.

“It was unwise to say ‘this was a good election’ hours after the voting ended. We were short on facts and figures; there wasn’t enough information about fraud,” said a senior Western official who helped the Afghan government organize the vote. “We still don’t have these answers. So saying it was a good, clean election, is premature.”

Karl Eikenberry, the U.S. ambassador to Afghanistan, speaking on CNN’s “State of the Union” on Sunday, said the Obama administration was waiting for results to be tallied. “We’re really not going to know for several more weeks exactly where we do stand in this process,” he said. “For now, we don’t know, and it’s for us to wait and see, and allow this process to move forward.”

“That elections took place at all is a notable achievement,” the European Union said in a statement on Saturday. “What we have observed was considered by our observers, with their methodology, good and fair…but free was not the case in some parts of the territory due to the terror installed.”

Complaints about electoral fraud center on the insurgency-wracked south and eastern parts of the country, where many polling stations were empty because of Taliban attacks and threats to punish anyone who dared to vote. Daoud Ali Najafi, the chief electoral officer of Afghanistan’s election commission, confirmed Sunday turnout was low in these provinces “with high security threats,” and said that a nationwide estimate of 50% participation in the election would be “optimistic.”

In the Wardak province south of Kabul, officials said that nearly all polling centers outside of district capitals had to be closed due to the violence. In Uruzgan province, only six out of 36 female polling centers opened, according to FEFA. The group said its observers witnessed the Taliban in the Kandahar province cut off the fingers of two voters. (Voters’ fingers in Afghanistan were marked with indelible ink.)

All these areas are predominantly Pashtun, and have traditionally been a stronghold of President Karzai, an ethnic Pashtun himself. Low turnout by the Pashtuns is likely to bolster Dr. Abdullah, who is more popular in the ethnic Tajik northern and western parts of Afghanistan.

Dr. Abdullah said over the weekend that Taliban violence — which has driven voters and international observers away from the polls in the south — has made it easier to stuff ballot boxes with fictitious votes in favor of the incumbent. Dr. Abdullah added in an interview that only “big rigging” could prevent him from securing an absolute majority.

Hamed Elmi, a Karzai spokesperson, denied these allegations and said that the Abdullah campaign was guilty of vote-rigging itself.

The findings of some independent observers appear in line with Dr. Abdullah’s claims. According to a confidential report made by members of one U.S. observer mission, ballot boxes from Kandahar and the Spin Boldak areas in the south — some of the worst insurgency flash points — are arriving at the electoral commission offices filled with 500 to 600 ballots each, indications of an exceptionally high turnout that doesn’t square with eyewitness accounts of deserted polling stations. Areas considered pro-Abdullah appeared to have higher turnout, making voter assessments more difficult.

Despite his complaints, Dr. Abdullah said he still has faith in Afghanistan’s electoral process, which requires the results to be vetted by the Electoral Complaints Commission, an independent body presided over by a Canadian officer, Grant Kippen.

Mr. Kippen said Sunday his commission received 225 complaints about instances of voter intimidation, violence, ballot-box tampering and interference by Afghan election-commission officials. Among these complaints, 35 have been assigned a “high priority” status, he said, because they were deemed “material to the outcome of the election results.”

Also speaking on CNN’s “State of the Union,” Chairman of the U.S. Joint Chiefs of Staff, Adm. Mike Mullen, said the situation in Afghanistan has deteriorated, but that the commanding general on the ground hasn’t yet asked for more troops.

“I’ve said that over the last couple of years, that the Taliban insurgency has gotten better, more sophisticated,” he said. He added that the commanding general on the ground, Stanley McChrystal, is still completing an assessment of his needs in the theater.