At the last military post before the Pakistan border, Afghan district governor Wali Shah explains why the insurgents seem untouchable. "The Pakistan government protects them," he said.
Shah has daily experience of a key problem threatening any future peace deal in Afghanistan, namely that Taliban rebels fighting US troops and the Kabul government live and operate in safety from Pakistan.
"When Pakistan says it will crack down on them, it is just pretending," he told AFP at Bowri Tana, a US and Afghan army post in the eastern province of Khost, 11 kilometres (seven miles) from the border.
"The Taliban are trained by the ISI (Pakistan's Inter-Services Intelligence agency) and come into Afghanistan to launch attacks. Pakistan doesn't want the violence here to stop. It doesn't want Afghanistan to develop."
For years, Afghans and Pakistanis have traded accusations of blame over the Islamist insurgents who pose a threat to security in both countries and seemingly criss-cross the porous border with impunity.
Pakistan was a key ally of the Taliban until joining the US-led "war on terror" after the September 11, 2001 attacks but has been accused by friend and foe alike of tacitly or, worse still, actively supporting Afghan insurgents.
Officials vigorously deny the allegations and point out there are 140,000 Pakistani troops committed in the northwest fighting a Pakistani Taliban insurgency -- leaving them too overstretched to do more.
But rebel safe havens in Pakistan infuriate Afghan President Hamid Karzai and remain a major obstacle to peace as the United States prepares to start withdrawing 33,000 troops by the end of summer 2012.
A diplomatic spat has also flared recently amid accusations from Kabul that Pakistani rocket attacks have killed dozens this month. The Afghan government says this may damage "improving trust and cooperation" between the two.
Pakistan says its security forces may have fired only a few accidental rounds while pursuing militants but also claims that insurgents from Afghanistan have crossed the border to attack security checkpoints.
Lieutenant Colonel Jesse Pearson, US commander along 120 kilometres of the border in Khost, does not duck the issue of Pakistan sheltering the Taliban and other Islamist groups such as the Haqqani network.
"Most attacks are commanded from Miranshah (in Pakistan)," he said during a meeting this week with Shah at Bowri Tana. "That is frustrating as we want to go after the enemy but we can't go across the border.
"Despite their advantage, it doesn't mean that we can't win. Indeed, it is clear to me that we are winning this war."
Pearson said he believed Afghanistan was reaching a "tipping point where the people reject terrorists and look to the government to provide a brighter future for their children."
Many Afghans are not so sure as 10 years after the fall of the Taliban regime, US President Barack Obama starts to cut troop numbers ahead of a 2014 deadline for all coalition combat forces to leave the country.
"If I am honest, things were better between 2001 and 2005 than today," said Shah, the governor of Khost's Gorbuz district. "I don't believe we can handle security by ourselves. Improvements are being made, but 2014? We will see."
US military officers in Khost admit that Afghan security forces are below standard and that Taliban infiltrators exist within the ranks who live and work with US troops.
"All ANSF (Afghan national security forces) are penetrated to some level," said Pearson after one IED was found near Bowri Tana in a spot that suggested inside knowledge of gaps in the military's surveillance capability.
"Senior police and army leaders know the issue, and are ready to compartmentalise operations so that not all their men have access to all information."
For district governor Shah, the best hope lies in increasing cross-border commerce which he believes would bring greater wealth to the area, as well as stability.
His district includes Ghulam Khan Gate, a road crossing similar to the famous Khyber Pass between northwest Pakistan and Kabul.
"The road is going to be improved and a new customs house will be built. We want to boost traffic from 80-100 trucks a day to 1,000," he said.
"I am optimistic we can hit that target within two years. It would change a lot of things."
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