The Afghan Taliban's leadership has dispersed to cities across Pakistan to avoid arrest after the recent detention of senior militants, officials and militants say. Western officials say the growing pressure on militant leaders, if maintained, represents one of the best hopes for undermining the twin insurgencies threatening Afghanistan and Pakistan. The dispersion of Taliban leaders is slowing the process of replacing the group's operations chief and effective No. 2, Mullah Abdul Ghani Baradar, say militants and tribal elders with ties to the insurgents. Mullah Baradar was arrested in late January, and at least three other major Taliban figures have since been picked up, along with a handful of second-tier leaders, U.S. and Pakistani officials say. The Afghan militants and the affiliated Pakistan Taliban have also faced major territorial setbacks from military offensives on both sides of the border over the past six months. Yet they remain potent forces, as evidenced by car bombings in both countries over the past two weeks. The Taliban is a highly decentralized movement; even without top commanders, fighters can skirmish, launch hit-and-run ambushes and bury improvised bombs along dirt roadstactics that have often stymied vastly superior military forces. But the leadership vacuum, says a senior North Atlantic Treaty Organization officer, should hamper the militants' ability to fight off major offensives, like the planned coalition move later this year to reassert control over Kandahar the Taliban's spiritual and strategic heartland in southern Afghanistan. "Foot soldiers will only be able to follow their last order," the officer said. "Their ability to conduct cohesive and coordinated operationsthe more organized and strategic stuffwill be significantly deteriorated," he said. Aghan President Hamid Karzai arrived Wednesday in Pakistan for talks likely to focus on how Pakistan's government can take a larger role in efforts to end the Taliban insurgency, including possible help training Afghanistan's nascent security forces, a senior Pakistani official said. Afghanistan is also pressing Pakistan to hand over Mullah Baradar, an Afghan national, and other detained Taliban leaders, although a Pakistani court earlier this month temporarily barred his extradition. Pakistan has been vague about the identities of most of the people it is holding. But authorities acknowledge arresting Mullah Baradar, the highest Taliban figure ever detained. Pakistani and U.S. officials say his most likely successor is Abdullah Gulam Rasoul, better known as Mullah Zakir, a former Guantanamo Bay detainee sent back to Afghanistan and released by authorities there in 2007 under murky circumstances. Mullah Zakir has since his release emerged as the Taliban's top military commander in southern Afghanistan, where the U.S.-led coalition is now focusing its latest surge. But U.S. officials believe he spends most of his time in Pakistan, and a Pakistani intelligence official said that "we're seeing and hearing a lot of confusion" in the Taliban's top ranks. "I don't think they are clear on the lines of authority right now," the official said. He said his assessment was based on human intelligence and communications intercepts. It was backed up by former and current militants and tribal elders with ties to the Taliban. "The shuras are totally split apart these days," said Izmat Ali Mr. Khan, a former militant who retains ties to his one-time compatriots. Shura is the common Pashto term for a leadership council. The Afghan Taliban's executive board, led by Mullah Muhammad Omar, is known as the Quetta Shura for the city in southwestern Pakistan where it is believed to have been based for most of the past nine years. The exact number and identities of people on the Quetta Shura is a closely guarded secret; at least three, perhaps four, of the people arrested recently were on the shura, say U.S. officials and experts. There are also subordinate shuras that oversee specific elements of the Taliban's operations. There's a military shura, a finance shura, a cultural affairs shura and a political shura, among others. Many Afghan Taliban leaders sit on multiple shuras. Taliban leaders began drifting away from Quetta in large numbers late last year amid reports the U.S. wanted to expand its campaign of missile strikes by drone aircraft beyond the narrow ribbon of tribal areas that run along Pakistan's northwestern border with Afghanistan, said a Pakistan intelligence official. Most shura members now live in vast ethnic Pashtun neighborhoods of Karachi, a teeming Arabian Sea port of about 16 million people, and in and around Multan, in central Pakistan, where allied jihadis are believed to be providing refuge. Mullah Barader was captured in Karachi in late January in a joint operation between Pakistan's Inter-Services Intelligence agency and the Central Intelligence Agency. Even though many leaders are believed to still live near one another, fear of arrest keeps them from meeting face-to-face in large groups, say people with ties to the militants. "You can't see more than three guys sitting together," said Gul Khan, a tribal elder in northwestern Pakistan with ties to the Haqqani network, a Taliban ally and major pillar of the Afghan insurgency. Some have simply dropped out of sight, cutting off contact with most colleagues, officials say. That appears to be the case with Amanullah Mehsud, a Taliban commander who serves as the liaison between the Afghan and Pakistan Taliban. He disappeared in Karachi in late February, according to relatives and Taliban members. They say believe he's been arrested; Pakistani officials say they aren't holding him. Leaders of the Pakistan Taliban, formerly known as the Tehrik-e-Taliban Pakistan, also began moving to Karachi and central areas late last year after the Pakistani military invaded South Waziristan, a major militant stronghold. "We are always on the lookout for them. We know some are here," said Collin Kamran Dost, the special home secretary for Sindh province, where Karachi is located. For U.S. officials, the major question now is what other moves, if any, Pakistan plans to make against militants hiding on its territory. U.S. officials have long alleged that elements of Pakistan's military and the ISI aid the Taliban, seeing it as useful proxy to combat the influence of archrival India in Afghanistan after an eventual American withdrawal from the region. Pakistan's sudden willingness to arrest the likes of Mullah Baradar surprised the American officials; Pakistani officials offered no public explanations for their apparent reversal. U.S. officials say they believe Pakistan, impressed by allied gains in Afghanistan, is now looking to hedge in the other direction. But "we're not winning yet," said the senior NATO officer. "We're making progress. The more we make, the more maybe we'll see help on that side," said the officer, speaking in the southern Afghanistan town of Marjah, the sight of the largest coalition offensive since 2001. Such optimism is tempered by clear evidence the Taliban and its allies retain the ability to strike deep inside both Afghanistan and Pakistan. On Wednesday, six Pakistanis working for the U.S. charity World Vision were killed when a dozen suspected militants lobbed hand grenades into their offices and then entered and opened fire, officials said. The charity confirmed the deaths and said it was suspending operations. Still, a Pakistani general cited his military's recent success against the Pakistan Taliban in the Bajaur tribal region as an example of "how we are punishing these miscreants." That may be the case. But Pakistan has twice in the past year declared victory in Bajaur, and U.S-led forces have repeatedly cleared areas in Afghanistan only to see the Taliban return. "They"meaning the U.S. and its Pakistani allies"are only boastful when they are winning," said Mr. Khan, the former militant.(WSJ)