12 May 2011 Last updated at 07:17 ET
What does Bin Laden death mean for Afghan war?
All four were friends from the same village of Afghan refugees in Pakistan
Taliban Conflict
Preparing Nato's exit
Can the insurgents be defeated?
Watch
Battle for loyalty
Who are the Taliban?
"The US military commander in Afghanistan has said the killing of Osama Bin Laden may weaken al-Qaeda's influence on the Taliban. Even so, warned Gen David Petraeus, Afghanistan could still become a potential refuge for international terror groups. Meanwhile, members of Congress have been calling for US troops to hasten their withdrawal. Paul Wood reports from Kabul on the course of the Afghan war now that Osama Bin Laden is dead."
link-
http://www.bbc.co.uk/news/world-south-asia-13352063