FACTBOX: Afghan review marked by divisions among Obama aides

(Reuters) - A White House review of war strategy in Afghanistan has underscored divisions among top advisers to President Barack Obama, who has also questioned what more troops will accomplish with a weak government in Kabul.

On one side are those who back proposals to send at least 30,000 more troops, including Defense Secretary Robert Gates and military chiefs, as part of an expanded counter-insurgency plan. This hinges on the Afghan public supporting the government in Kabul and turning against the Taliban.

Skeptics including Vice President Joe Biden and the U.S. ambassador to Afghanistan question whether a troop increase will work given doubts about Afghan President Hamid Karzai's legitimacy. They point to August's fraud-marred election and long-standing concerns about corruption and weak governance.

Here's where some of the key players stand:

GENERAL STANLEY MCCHRYSTAL, the top U.S. and NATO commander in Afghanistan, has recommended an increase of 40,000 troops as the minimum for a counter-insurgency to prevail. There are already 68,000 U.S. troops in Afghanistan and another 40,000 from allied nations.

VICE PRESIDENT JOE BIDEN is the leading skeptic within the Obama administration of McChrystal's recommendation of a troop increase. Behind the scenes, Biden sometimes plays the role of devil's advocate. Though he is known for his public gaffes, Biden is considered within the White House a knowledgeable voice on foreign affairs, given his status as former chairman of the Senate Foreign Relations Committee.

Biden's approach on Afghanistan would involve narrowing the counter-insurgency mission and concentrating more heavily on the counter-terrorism mission of pursuing al Qaeda targets in Pakistan and along the Afghan border. This option would involve little or no change to U.S. troop levels for now.

U.S. AMBASSADOR TO AFGHANISTAN KARL EIKENBERRY, who commanded U.S. troops in Afghanistan in 2006 and 2007, has expressed in writing his deep concerns about sending more U.S. troops to Afghanistan until the Karzai government demonstrates it is willing to aggressively attack corruption and mismanagement.

DEFENSE SECRETARY ROBERT GATES, whose views could sway Obama's, has signaled his support for a 30,000-troop increase, officials said. If bolstered by smaller commitments of trainers from NATO allies, this option come close to the force requirements laid out by McChrystal for stemming Taliban gains. Gates has made clear a decision on a troop increase cannot wait for the Afghan government to gain legitimacy. That, Gates said, would take much longer.

ADMIRAL MIKE MULLEN, chairman of the U.S. military's Joint Chiefs of Staff, has expressed a desire to support McChrystal's troop request to the maximum extent possible, putting him more squarely in the 40,000 troop increase camp. But Mullen has said Karzai's legitimacy among the Afghan people, key to any successful counterinsurgency, was "at best, in question right now and, at worst, doesn't exist."

SECRETARY OF STATE HILLARY CLINTON has a close rapport with Gates and was expected to side with him in the internal debate. She has warned if the Taliban were able to retake control of Afghanistan or big swaths of it, "there is every reason to believe" al Qaeda would once again secure a sanctuary there, a concern shared by Gates but that the White House national security adviser has sought to downplay.

WHITE HOUSE NATIONAL SECURITY ADVISER JAMES JONES, whose job is to mediate among the foreign policy voices within the administration, has said McChrystal's recommendation is one of several options under consideration and not a "fait accompli." He has said publicly he does not foresee a risk that the Taliban would regain control of Afghanistan and emphasized that the United States has made big strides against al Qaeda militants there.

RICHARD HOLBROOKE, U.S. SPECIAL ENVOY FOR AFGHANISTAN AND PAKISTAN, has privately voiced concern about the risk of under-resourcing the military mission, particularly along the border with Pakistan. He is frustrated by what he and his advisers see as Karzai's refusal to seriously tackle corruption. U.S. officials question whether a counter-insurgency strategy can be effective if the Karzai government is not seen as legitimate.

(Reporting by Adam Entous and Caren Bohan; editing by Sue Pleming and Cynthia Osterman )