Suspected Islamist militants blew up a bridge in northwestern Pakistan's Khyber Pass Tuesday, cutting the main route for supplies bound for Western forces in land-locked Afghanistan, Pakistani officials said.
The easiest land route for supplies and military equipment into Afghanistan is by ship to the Pakistani port of Karachi, and then by truck through Pakistan and into Afghanistan.
But militant attacks that intensified last year have forced the U.S. and other Western forces to look for alternatives through central Asia and Russia into northern Afghanistan.
Following are some facts about the Pakistani routes and the alternatives:
THE ROUTES AND SUPPLIES
There are two routes through Pakistan into Afghanistan, one through the Khyber Pass in northwest Pakistan to the border town of Torkham and on to Kabul. The other goes through Pakistan's Baluchistan province to the border town of Chaman and on to the southern Afghan city of Kandahar.
The U.S. military and NATO have not given details of the supplies they get via Pakistan or a breakdown of how much comes on the two routes. The U.S. Defense Department says the U.S. military sends 75 percent of supplies for the Afghan war through or over Pakistan, including 40 percent of fuel.
Pakistani customs officials say under normal circumstances about 300 trucks with Western force supplies travel through the Khyber Pass crossing at Torkham every day, compared with about 100 through the Chaman crossing.
The responsibility for equipping forces within NATO's Afghan force lies with each country. Some imported supplies for the fledgling Afghan armed forces, which the United States and its allies are building up, also come through the Pakistani routes.
Khyber is one of seven so-called agencies in Pakistan's Federally Administered Tribal Areas. The area is awash with weapons and inhabited by ethnic Pashtun tribes.
Under a system inherited from colonial Britain, a government "political agent" administers through tribal elders meant to maintain peace and keep open the road through the pass to the border.
Pakistani Taliban stepped up attacks on trucks last year. They have also attacked staging areas outside Peshawar and at Torkham. The attacks have disrupted supplies but, before Tuesday, the route has only been briefly closed twice since September.
The route through Chaman has been largely free of attacks on the Pakistan side, although the section passing through Afghanistan from the border town of Spin Boldak to Kandahar has seen Taliban attacks.
The chief of the U.S. Central Command, General David Petraeus, said last month agreements had been reached for new transport routes for Western Forces into northern Afghanistan through Central Asian states and Russia. He did not give details.
Apart from Pakistan, Afghanistan has a border with Iran to the west, Turkmenistan to the northwest, Uzbekistan and Tajikistan to the north, and a sliver of remote mountainous territory with China in the far northeast.
Afghan-bound supplies coming by ship would have to dock at ports in the Mediterranean (Turkey), the Black Sea (Russia or Georgia), or at other Russian ports.
From Russia, goods would most likely have to cross Kazakhstan and Uzbekistan and into northern Afghanistan.
Another possibility for goods off-loaded in Georgia or Turkey could be through Azerbaijan, then across the Caspian Sea to Turkmenistan and then into northwest Afghanistan.
Iran could provide a convenient and cheap link from its port of Chabahar to western Afghanistan but tense ties with the United States would appear to rule out that route for military supplies for the U.S.-led effort in Afghanistan.
(Writing by Robert Birsel; Editing by Jerry Norton)