WASHINGTON - In a remarkable parallel with a similar turning point in the Vietnam War 44 years ago, President Barack Obama will preside over a series of meetings in the coming weeks that will determine whether the United States will proceed with an escalation of the Afghanistan War or adjust the strategy to reduce the U.S. military commitment there.

A U.S. Marine from Bravo Company, 1st Battalion 5th Marines, stands with local children and men, as he guards a nearby meeting between a Marine officer and local elders, in Nawa district, Helmand province, southern Afghanistan, Thursday, Sept. 24, 2009. (AP Photo/Brennan Linsley) The meetings will take place in the context of a request from Gen. Stanley A. McChrystal, the top commander in Afghanistan, for 40,000 additional troops, which reached Washington over the weekend. That would bring the total U.S. troop strength in Afghanistan to 108,000 - nearly a 60-percent increase.

Obama has hinted at serious doubts about being drawn more deeply into the war in Afghanistan, and administration officials have signaled that a key issue is whether the proposed counterinsurgency war could be won.

A plan backed by Vice President Joe Biden to scale back U.S. forces in Afghanistan and to focus more narrowly on al Qaeda was one of the options discussed at a Sept. 13 meeting of top administration officials, according to a report in The Age (Melbourne) Friday. That plan would reportedly depend on U.S. Special Forces to track down al Qaeda and ratchet down the counterinsurgency war.

But the decisions that emerge from the coming meetings are more likely to be shaped primarily by the concerns of the military and of the White House about being blamed for a defeat in Afghanistan that now seems far more likely than it did just six months ago.

In that regard, the approaching White House meetings recall similar consultations in June 1965, when President Lyndon B. Johnson and his civilian advisers responded to a request from Gen. William Westmoreland and the Joint Chiefs of Staff for a major troop increase in South Vietnam by discussing ways to limit the U.S. military commitment in South Vietnam.

President Johnson, Secretary of Defense Robert S. McNamara and National Security Adviser McGeorge Bundy were all doubtful that the war could be won even with a much larger troop commitment.

Johnson, like Obama today, also had an alternative to further escalation of the war - a proposal for a negotiated settlement from Undersecretary of State George Ball, which was strongly opposed by others in Johnson's national security team, including McNamara.

But a few weeks later, Johnson went along with an open-ended troop commitment in Vietnam because he was unwilling to face the likelihood of charges by the military that he was responsible for the loss of South Vietnam.

In a series of appearances on Sunday talk shows Sept. 20, Obama signaled that he wants to avoid getting more deeply involved in Afghanistan, although he left the door open to approving more troops. "Until I'm satisfied that we've got the right strategy," he said on NBC's Meet the Press, "I'm not going to be sending some young man or woman over there - beyond what we already have."

In a news conference Friday, Obama raised the issue of whether there is "a sense of legitimacy... among the Afghan people - for their government," without which, he said, the U.S. task would be "much more difficult", obviously referring to President Hamid Karzai's rigging of last month's election.

Obama is questioning whether a counterinsurgency war is feasible under the existing conditions in Afghanistan. In a Sep. 21 interview with Josh Rogin of The Cable that was obviously cleared with the White House, Assistant Secretary of Defense Michele Flournoy referred to "an uncertain outcome" in Afghanistan.

In an initial round of debate on Afghanistan during Obama's first weeks last January and February, Biden argued that the war plan would be far too costly and might not succeed, as Michael Crowley reported in the Sept. 24 New Republic.

Secretary of State Hillary Clinton, Secretary of Defense Robert Gates and Afghanistan coordinator Richard Holbrooke supported the military's proposal, however. In the end, Obama compromised with the military, approving 17,000 of the 30,000 troop request, even in the absence of a clear strategy.

But the White House let it be known that it was not committed to a full-fledged counterinsurgency war in Afghanistan. Obama's insistence in his Mar. 27 speech that the U.S. objective in Afghanistan was to defeat al Qaeda now appears to have been a sign that he was determined to keep his options open.

McChrystal's "initial assessment" declaring that "failure to provide adequate resources" would probably result in "mission failure", was sent to Washington Aug. 31, but weeks passed without any signal from the White House that it was ready to entertain a troop request.

That provoked complaints from McChrystal's staff expressing unhappiness with the delay, according to a report by McClatchy newspapers Pentagon correspondent Nancy Youssef Sep. 18.

Then McChrystal's assessment was leaked to the Washington Post's Bob Woodward, generating a big headline in the Sept. 21 Washington Post about McChrystal's warning of "mission failure". That leak was obviously aimed at making it more difficult for Obama to turn down his eventual troop deployment request.

But McChrystal's "initial assessment" presents such a formidable array of obstacles to the success of a counterinsurgency war in Afghanistan that it could be seen as an invitation to the president to reject the strategy.

Both leaking such a relatively bleak assessment and requesting 40,000 more troops may have been aimed primarily at ensuring that McChrystal and his boss, Gen. David Petraeus, cannot be blamed for defeat. Petraeus and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, have closed ranks behind McChrystal's strategy and can be expected to endorse his troop request.

"Military commanders are always going to ask for more troops," says Larry Korb, senior fellow at the Center for American Progress and a former assistant secretary of defence. "They figure if they don't ask for more, and it doesn't go well, they could be blamed."

For the White House, fears of being blamed for having failed to provide sufficient troops are exacerbated if key national security officials are supporting the military position rather than the president. In June 1965, Johnson initially leaned toward holding the line against open-ended escalation, because he thought he had the support of his defence secretary, McNamara, which he felt gave him the needed political cover.

But when McNamara shifted his position to one of support for the troop level requested by the Joint Chiefs of Staff, Johnson gave in to the military.

Secretary of Defense Robert Gates, who was chosen by Obama to provide "political cover" on national security policy, may play the same spoiler role as McNamara did in 1965 in regard to Obama's desire to avoid escalation.

Gates has remained publicly undecided on the troop increase issue. But on ABC's "This Week" Sunday, he declared that being defeated by the Taliban in Afghanistan would have "catastrophic effects", by "energizing" al Qaeda recruitment, operations and fundraising.

Gates, Clinton and Holbrooke are likely to press Obama to go along with at least a large part of the McChrystal troop request, arguing that the war cannot be abandoned. They will argue that the Obama's presidency cannot survive an open breach with the military, and that Republican senators are already poised to attack Obama as weak if he fails to provide whatever McChrystal requests.

Obama could still argue that conditions in Afghanistan have changed, and that U.S. objectives there must now be adjusted. But he would have to do battle with his military leadership, the Republicans and his own national security advisers.

The high political price that the forces arrayed behind the war in Afghanistan are prepared to exact on Obama for reining in the present war may compel him to compromise with them once again.

Gareth Porter is an investigative historian and journalist specialising in U.S. national security policy. The paperback edition of his latest book, "Perils of Dominance: Imbalance of Power and the Road to War in Vietnam", was published in 2006.