Afghanistan drawdown risky, US joint chiefs head says

Adm Mike Mullen said leaving troops in place was "the safer course", but added he supported the president's decision.

Secretary of State Hillary Clinton said Mr Obama had kept a pledge to begin withdrawals by July 2011.

On Wednesday Mr Obama announced the withdrawal of 33,000 troops from Afghanistan by September 2012.

Afghan President Hamid Karzai welcomed the move, but the Taliban dismissed it as "symbolic" and vowed to continue fighting until all foreign forces left.

In a series of interviews and congressional hearings on Thursday, senior US officials lent their support for Mr Obama's decision to remove about one-third of the US troops from Afghanistan by the end of next summer.

Defence Secretary Robert Gates acknowledged that the president had taken account of waning domestic political support when making the decision, AFP news agency reported.