Barack Obama is preparing to decide on additional troop deployments to Afghanistan as he faces waning US public support for the war that has entered its ninth year.

The rising anti-war sentiment has prompted Robert Gates, the defence secretary, to urge the US president's advisers on Afghanistan to express their views in private, following last week's public request by General Stanley McChrystal, the top US commander in Afghanistan, for more troops.

Al Jazeera's Sebastian Walker reports.