Obama expected to announce troop withdrawal

The US President Barack Obama is to announce his timetable for pulling American troops out of Afghanistan in a TV address to the nation tonight.

President Obama is expected to re-affirm his plan to transfer control of the country's security to Afghan forces by 2014.

But he must first reconcile serious differences over the strategy with his military chiefs.

US Defence Secretary Robert Gates has said the President is in "a tricky position".