US 'must step up' Bin Laden hunt in Afghanistan

The top US commander in Afghanistan says al-Qaeda cannot be defeated until Osama Bin Laden is killed or captured.

Gen Stanley McChrystal said President Barack Obama's deployment of 30,000 extra troops to Afghanistan meant success was possible. But he said the mission was "undeniably difficult" and the next 18 months would be crucial.

Jonathan Beale reports.