Barack Obama and Pentagon split on Afghanistan pullout

Barack Obama is set to reject the advice of the Pentagon by announcing on Wednesday night the withdrawal of up to 30,000 troops from Afghanistan by November next year, in time for the US presidential election.

The move comes despite warnings from his military commanders that recent security gains are fragile. They have been urging him to keep troop numbers high until 2013.

The accelerated drawdown will dismay American and British commanders in Kabul, who have privately expressed concern that the White House is now being driven by political rather than military imperatives.

"This is not something we feel entirely comfortable with," a Whitehall official told the Guardian.

Obama's nationally televised address, the sixth he has given since becoming president, is intended to mark the beginning of the end of American military deployment in Afghanistan, from a present high of almost 100,000 troops.