The announcement today that the United States will deploy up to 15,000 more troops to Afghanistan is just the latest signal of the Pentagon's seeming support for Barack Obama's strategy to fight Al Qaeda in the region. Following by just weeks Obama's latest call to send at least two more brigades of American troops there, the request by U.S. commanders again confirmed Obama's assertion, one denied by John McCain, that Iraq represents a "zero sum game" for scarce American military resources.

That request by General David McKiernan, the commander of NATO forces in Afghanistan, comes on the heels of Joint Chiefs Chairman Michael Mullen's agreement with Senator Obama that the situation along the Pakistan frontier is "precarious and urgent." The need is urgent indeed: in July, 9 American troops were killed in an insurgent raid that overran a U.S. border outpost; yesterday, 10 French soldiers were killed in a Taliban attack. In response, General McKiernan hopes to bolster the 101st Airborne Division with up to three brigades.

But as U.S. News reported this morning, the challenge for McKiernan and his staff is finding the needed troops. While their ask has been approved, a defense official noted, "Now that means we just need to figure out a way to get them there." As McKiernan himself made clear, the only "way" is to get the troops from Iraq:

Finding those particular troops to supplement the 101st, however, depends on conditions and troop levels in Iraq, adds McKiernan, who took over the NATO command in June. "That's really a zero-sum decision."

In early July, Admiral Mullen admitted as much. On the very day that 2,200 U.S Marines learned their tours in Afghanistan will be extended by 30 days, Mullen told reporters that the United States could only deploy more forces there by first drawing down from Iraq:

"I don't have troops I can reach for, brigades I can reach, to send into Afghanistan until I have a reduced requirement in Iraq. Afghanistan has been and remains an economy-of-force campaign, which by definition means we need more forces there."

And on that point, Barack Obama and John McCain part company. From almost the inception of his campaign, Obama has argued that the diversion of U.S. military assets from Afghanistan to Iraq meant that "the people who were responsible for murdering 3,000 Americans on 9/11 have not been brought to justice." In a June speech, Obama highlighted McCain's denial of this inescapable point:

"We had al Qaeda and the Taliban on the run back in 2002. But then we diverted military, intelligence, financial, and diplomatic resources to Iraq. And yet Senator McCain has said as recently as this April that, 'Afghanistan is not in trouble because of our diversion to Iraq.' I think that just shows a dangerous misjudgment of the facts, and a stubborn determination to ignore the need to finish the fight in Afghanistan."

McCain's denial - and disagreement with the Pentagon - over the trade-offs in sending more U.S. forces to the Afghan-Pakistan frontier doesn't end there. While McCain reversed course and mimicked Obama's call for more troops in Afghanistan, he fudged as to whether they should come from the United States or its NATO allies. Cornered on the question of where he intends to come up with the needed reinforcements, McCain feebly responded:

"We need to work that out. We need to have greater participation on the part of our NATO allies, as I said in my opening remarks today, and we need a lot more help."

Still, McCain's confused and contradictory statements didn't stop him from calling for "surge for Afghanistan" on July 15. (As Steve Benen rightly noted, a "surge" is now John McCain's prescription for all ills, foreign and domestic.) But as General McKiernan reiterated today, the United States doesn't need a surge in the fight against Al Qaeda in Afghanistan, but a long-term commitment:

He disputes the notion that the three brigades on the way represent a troop "surge" for Afghanistan, predicting the need for an extended involvement of a larger force. "I've certainly said that we need more security capabilities," he says. "But I would not use the term 'surge,' because I think we need a sustained presence."

At every turn, the Pentagon has backed Barack Obama's approach to defeating Al Qaeda and the Taliban in the Afghanistan-Pakistan border regions. While John McCain in February ridiculed Barack Obama's call for unilateral American strikes against Al Qaeda targets within Pakistan, the Bush administration and the Pentagon soon adopted Obama's thinking. (Just today, an apparent U.S. missile strike killed 18 militants in South Waziristan.)

Earlier this week, the Center for American Progress and Foreign Policy released their annual "Terrorism Index." Their survey of 100 bipartisan foreign policy analysts found that 51% believe Pakistan will be the next Al Qaeda stronghold; exactly zero said "Iraq." 80% said the U.S. had not dedicated enough resources to Afghanistan, while 69% called for redeploying the majority of American troops from Iraq over the next 18 months.

All of which sounds like it could have come from Barack Obama. Or, as was made clear again today, from the Pentagon.