Washington  - US President Barack Obama held meetings Wednesday with top advisors to assess the war in Afghanistan and decide the next steps in tackling the increasingly difficult conflict.

The top US commander in Afghanistan, General Stanley McChrystal, will be participate in the meeting via video-conference from Kabul.

Other participants included Defence Secretary Robert Gates, Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, Vice President Joe Biden, Secretary of State Hillary Rodham Clinton, national security adviser James Jones and General David Petraeus, commander of US forces in the Middle East and South Asia.

Obama is said to be weighing options for regaining momentum in Afghanistan, where casualties for US troops have exceeded the numbers in Iraq for nearly a year amid fighting with the resurgent Taliban.

"The administration wants to go through and ensure for the American people that we're making the very best decisions to protect our national security," White House spokesman Robert Gibbs said, adding that the president is taking a "top to bottom" approach.

Obama met Tuesday with NATO Secretary General Anders Fogh Rasmussen, and the two men reaffirmed commitments to prevailing in Afghanistan. The White House said it could be several weeks before Obama's reaches a final decision.

McChrystal provided a classified report to Obama in early September. According to the Washington Post, the general warned Obama that additional troops are needed within the next 12 months or the conflict will "likely result in failure."

McChrystal has reportedly requested an additional 40,000 soldiers on top of the more than 60,000 US troops already there. Some Democratic lawmakers have said they oppose sending more troops as polls show public support for the war is weakening.  dpa