According to reports, between 25-40 oil tankers carrying fuel from Pakistan to NATO forces in Afghanistan were destroyed March 23, after an explosion took out the trucks in a parking lot near the Khyber Pass connecting Pakistan to the eastern portion of Afghanistan. No group has taken credit yet, but oil tankers are a target for Taliban forces active in Pakistan's North West Frontier Province, and a Pakistani official recently said this March that "Up to three oil tankers were either destroyed or damaged every month in similar attacks over the past twelve months". Another tanker was destroyed in the same area March 18 when a roadside bomb exploded.
This is another great way for Taliban forces to hamper NATO ISAF efforts in Afghanistan, both those assigned to reconstruction and combating militants in the southern and eastern parts of the country. Whether the attack was carefully planned or whether it was a target of opportunity - the explosions took place in a parking lot by the border, and news reports aren't too clear on the security and protection available at the time - it offers another example of why a resurgent Taliban in Pakistan is dangerous for NATO forces in Afghanistan.
Lots of food, fuel and other supplies for NATO have to be transported through the Khyber Pass, which leaves them open to easy attack. Taliban forces are active at both ends of the pass, in Pakistan and Afghanistan, and love to take pot shots at passing trucks with rocket propelled grenades, rifles and grenades.
Still, this doesn't mean that the trucks are left unprotected. The U.S. military has often described the Khyber as a "critical crossing place", and both NATO and Pakistani forces attempts to step up security in the region have had some success.
The point remains that success in Afghanistan depends heavily on getting supplies into Afghanistan through Pakistan. NATO is stretched dangerously thin as it is, and there is a continual shortage of member countries willing and able to commit troops for more than training and reconstruction operations. Pakistan's military has a hard enough time justifying actual troop deployments to the heavily tribal-controlled areas on its border with Afghanistan. Hence, if Taliban militants really want to make life hard for NATO, they can step up attacks (or even attempted attacks), forcing either NATO or Pakistan's military to commit troops to security.
If anyone could find some real statistics for just how much food, fuel and whatnot moves into Afghanistan through Pakistan via ground transport, that'd be awesome.