Two sophisticated Taliban raids on NATO trucks in Pakistan have exposed the dangerous vulnerability of the vital supply route for international troops in Afghanistan through the legendary Khyber Pass.

Hundreds of vehicles were destroyed in two daring and well-planned attacks on terminals in northwest Pakistan -- at a time the United States is preparing to almost double the size of its force in landlocked Afghanistan.

The bulk of the supplies and equipment required by NATO and US-led forces battling the Taliban insurgency is shipped to Pakistan''s largest port, Karachi in the south.

From there, the containers of food, fuel, vehicles and munitions are taken by truck to the city of Peshawar before being transported through Pakistan''s restive tribal areas to Afghanistan via the Khyber pass.

It makes the famous 50-kilometre (30-mile) mountain pass -- used since the time of Alexander the Great -- indispensable to international forces.

But the road passes through the heart of Pakistan''s tribal zone, a hideout for militants since the ousting of Afghanistan''s Taliban regime at the end of 2001.

NATO and the US-led force said they expected Pakistan to increase security after hundreds of militants armed with rocket launchers and automatic weapons attacked the terminals, overpowering their guards and destroying vehicles and supplies.