Pakistani security personnel stop trucks carrying supplies for NATO forces in neighboring Afghanistan at Takhtabeg check post in Pakistani tribal area of Khyber, Pakistan, on their way to Torkham border post on Saturday, Nov 26, 2011. Pakistan on Saturday accused NATO helicopters of firing on two army checkpoints in the northwest and killing 25 soldiers, then retaliated by closing a key border crossing used by the coalition to supply its troops in neighboring Afghanistan. (AP Photo/Muhammad Sajjad)

Photo by: Muhammad Sajjad

Pakistani security personnel stop trucks carrying supplies for NATO forces in neighboring Afghanistan at Takhtabeg check post in Pakistani tribal area of Khyber, Pakistan, on their way to Torkham border post on Saturday, Nov 26, 2011. Pakistan on Saturday accused NATO helicopters of firing on two army checkpoints in the northwest and killing 25 soldiers, then retaliated by closing a key border crossing used by the coalition to supply its troops in neighboring Afghanistan. (AP Photo/Muhammad Sajjad)