KABUL, Nov 26 (Reuters) – NATO helicopters attacked a military checkpoint in northwest Pakistan on Saturday, killing up to 28 troops and prompting Pakistan to shut the vital supply route for NATO troops fighting in Afghanistan, Pakistani officials said.

NATO supply trucks and fuel tankers bound for Afghanistan were halted at Jamrud town in the Khyber tribal region near the city of Peshawar hours after the raid, officials said.

Following are some facts about the Pakistani supply routes for NATO forces fighting in Afghanistan and the alternatives:

THE ROUTES AND SUPPLIES

There are two routes into Afghanistan from Pakistan, one across the Khyber Pass to the Afghan 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, and former Taliban stronghold, of Kandahar.

Between them these two routes account for just under one third of all cargo that the NATO-led International Security Assistance Force (ISAF) ships into Afghanistan.

Just over one third of all cargo goes on routes dubbed the “northern distribution network” through Central Asia, and the Caucasus or Russia. The remaining 31 percent is flown in.

KABUL (Reuters) – Afghanistan is likely to need around $7 billion a year from the international community to help pay its security and other bills long after foreign troops leave, even if two large mines start production as planned, the World Bank said on Tuesday.

That annual spending, projected for the decade to 2021, does not include the cost of thousands of foreign troops expected to stay in Afghanistan to support and train Afghan forces after 2014, the deadline for NATO-led combat soldiers to return home.

The gap in how much money the Afghan government can raise and how much money it needs to fight a powerful insurgency while trying to develop one of the world’s poorest nations will be the equivalent of a quarter of national income by 2021.

This is under a “cautiously optimistic” scenario where agriculture becomes more efficient, a large copper mine and another large iron ore mine are opened on schedule, taxes increase and security does not get any worse.

None of these are guaranteed, and without them the growth will be slower and the funding gap larger, the World Bank warned in a report “Transition in Afghanistan: Looking Beyond 2014.”

Aid, which in 2011 was nearly $16 billion, will decline along with troop numbers as the West scales down its presence in Afghanistan. But the United States and its allies face a serious financial burden for many years after the official end of combat operations.

The World Bank forecasts that with firm economic growth the gap will still average around $7 billion a year after 2014.