The leak of Gen. Stanley McChrystal's sober assessment of the war in Afghanistan puts greatly increased pressure on President Obama in weighing whether to press on with the ambitious counterinsurgency recommended or chart a new direction.

McChrystal, only recently sent to Kabul as U.S. and NATO commander to tackle the revitalized Taliban insurgency, doesn't mince words in his previously secret 66-page document. He warns Obama that unless he basically stays the course by providing additional American troops and other resources, the outcome "is likely to result in mission failure."

The leak, obtained by The Washington Post, suggests opposition within the administration to anything resembling the 2007-08 surge in Iraq, particularly with the political uncertainty in Afghanistan in the wake of the challenged re-election of President Hamid Karzai.

It comes on the heels of a recent statement by Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, also indicating that the situation "probably needs more forces." But that did not prevent Obama from saying on his Sunday round of television talk shows that he will first assess the validity of the whole Afghan mission and strategy before deciding on troop levels.

The president, in fact, left the impression that he is doing basic soul-searching on whether this is the time to reconsider the whole role of the American involvement in the region, initiated in the wake of, and justified by, the 9/11 terrorist attacks.

In his CNN appearance, he pointedly asked, "Are we pursuing the right strategy?" And on NBC he said unless he was "satisfied" about that, he wasn't going to send any more young Americans in harm's way. He indicated that if the strategy was aimed at the al-Qaida perpetrators he would proceed, but if not he wasn't going to be in Afghanistan just for the sake of being there, or just "sending a message" that America was there "for the duration."

The original motivation for going into the country remains valid, and successes have been claimed in diminishing al-Qaida's strength and effectiveness. But the fact that Osama bin Laden remains alive and uncaptured stands as a mocking reminder of the declared and unfinished business of the previous administration.

The longer the war against the Taliban takes on the appearance of a replay of the concerted effort at nation-building that drags on in Iraq, the harder it will be for Obama to justify the greater engagement sought by McChrystal.

This is particularly so as American casualties in Iraq, while greatly reduced, continue to trickle in.

Congress and much of the public may well be able to accept intellectually that pressing on in Afghanistan is a legitimate mission unaccomplished, and nothing would bolster support at home more than getting bin Laden. But short of that, the struggle in the Afghan/Pakistani theater may seem increasingly a battleground devoid of basic American self-interest.

The most recent Washington Post/ABC News poll found 51 percent of Americans surveyed now say the war is "not worth fighting," and within Afghanistan itself, the same resentment of the presence of U.S forces seen in Iraq — more as occupiers than liberators — magnifies the difficulty for the American military stationed there.

Liberal Democrats in Congress who attempted without success to bring about swifter withdrawal from Iraq eye with wariness and even trepidation the Pentagon shift of emphasis and manpower from Iraq to Afghanistan. They see it as another indication of revisiting the Vietnam-era thinking of mindless escalation.

But Obama, for all his early characterization of Iraq as "a dumb war" that never should have been fought, has never bought into abandonment of the mission in either Iraq or Afghanistan. His response seems much more likely to proceed in the latter with a cautious and disciplined counterinsurgency short of a Bush-like surge that may not satisfy either the hawks or the doves.

In the end, Obama's desire to pursue his own ambitious domestic agenda, something not conspicuously present in the George W. Bush years, may well keep him more determined to find a respectable exit strategy not predicated on Bush's elusive quest of a vaguely defined "victory."