By Jonathan Marcus
Diplomatic correspondent, BBC News
An attack on Sunday destroyed more than 90 supply lorries
Nato and US military commanders are exploring options for supplies into Afghanistan after recent attacks on logistical depots in Pakistan.
The attacks on crucial supplies to forces in Afghanistan have highlighted the route's growing vulnerability.
However, political and logistical difficulties mean that Pakistan is likely to remain the transit route of choice for the foreseeable future.
Some 75% of the supplies for Afghanistan pass through Pakistan.
Given the staggering scale of the logistical operation supporting Nato and US forces in Afghanistan, the supplies destroyed in the recent attacks near Peshawar were a drop in the ocean.
Supplies routes through Pakistan are becoming increasingly insecure
Supplies for Afghanistan pass through Pakistan after being off-loaded from ships at the port of Karachi.
Much of the fuel used by Western forces also comes from refineries in Pakistan and for good reason.
Pakistan represents the shortest land-route to places like Kandahar and Kabul.
But the growing insurgency inside Pakistan and the failure of the authorities there to deal with it effectively mean that alternatives are being explored.
Some fuel already comes from refineries in Azerbaijan and Turkmenistan.
Nato has an agreement with Russia on shipping supplies through its territory and individual Nato members like Germany and Spain have concluded their own bilateral agreements on trans-shipment with Moscow.
Nato though is uneasy about becoming too dependent upon Russia.
An alternative route would see containers being shipped across the Black Sea, then going by rail through Georgia to Azerbaijan's Caspian Sea ports and then by road through Turkmenistan.
The oil would go either directly to Afghanistan or through Kazakhstan and Uzbekistan.
But this could be a logistical and political nightmare and it is far from clear that the infrastructure could sustain the volume of traffic needed.
For now the focus is going to be on getting the authorities in Pakistan to step-up security surrounding the existing supply routes.