Just a few hours walk from where a US missile strike targeted al-Qaeda's No. 2 leader, soldiers lounge on the ground, looking bored and taking no notice of people who stroll across the border into Afghanistan.
Both Pakistan and Afghanistan say they have stepped up security along this front line in the war on terror, but a reporter who went to the region on Monday saw little scrutiny of travelers' bags or IDs -- suggesting there's not much to stop al-Qaeda militants from slipping across.
No fence separates Afghanistan from Pakistan along much of the 2,450km-long frontier. At the border post at the top of Nava Pass, in Afghanistan's Kunar Province, a rusting gate is all that divides the two countries.
Up to 1,000 people go through the checkpoint daily, and about 400 more are believed to cross along numerous tiny paths that wind their way through the rugged mountains, said Mohammed Akbar Ahamadwal, Kunar's border security commander.
Most of those who cross illegally are merely herding flocks of sheep between pastures or tribesmen with relatives in both countries, he said.
But not all are harmless.
"Our forces have had many gunbattles with terrorists we have caught sneaking across the border," Ahamadwal said on a border tour in a heavily armed convoy. "Al-Qaeda and Taliban come across, launch attacks then flee back."
Kunar and the neighboring Bajur region of Pakistan have long been militant hideouts because of their inaccessible mountains and caves _ and the sympathies of residents. Many are Pashtuns, the same ethnic group as Afghanistan's former Taliban regime. Some are Wahhabis, followers of a strict brand of Sunni Islam.
Kunar is where US forces suffered their deadliest blow in Afghanistan since they ousted the Taliban in 2001 for sheltering Osama bin Laden. Last June, three Navy SEAL commandos were killed in an ambush and 16 troops sent to rescue them died when their chopper was shot down -- attacks claimed by the Taliban.
An Afghan army commander in Kunar, speaking on condition of anonymity because he is not authorized to talk to the media, said he often gets intelligence reports that Ayman al-Zawahri, bin Laden's top lieutenant, and "other big al-Qaeda people are in these mountains."
Al-Zawahri is believed to have been the target of a CIA-directed missile attack from a Predator drone on Friday across the Pakistani border in the village of Damadola. Pakistani intelligence officials say he'd been invited to a dinner there, but didn't show up. Three houses were destroyed and 17 people killed, sparking angry protests in Pakistan.
US forces often patrol Kunar with Afghan soldiers and go on joint operations against suspected militant bases in the mountains. Yet most of the border-watching is done by Afghanistan and Pakistan, which have both dispatched extra troops.
Pakistan now has more than 70,000 forces in its tribal regions -- although few were in evidence in Bajur after Friday's missile strike.
A senior army official, who declined to be named because of the sensitivity of the matter, maintained troops were working undercover because of residents' anger over the airstrike.
In Kunar, a 1,000-member tribal militia force was established last month to patrol the frontier, provincial Governor Assadullah Wafa said in the regional capital Asadabad, near a large US military base that houses hundreds of Marines and commandos.