In March, President Obama thought that defeating al Qaeda and the Taliban was critical to national security. "[I]f the Afghan government falls to the Taliban -- or allows al Qaeda to go unchallenged," he warned, "that country will again be a base for terrorists who want to kill as many of our people as they possibly can."

In August, the president reiterated the need to succeed in Afghanistan, when he told the Veterans of Foreign Wars, "This is not a war of choice, but a war of necessity." He went on to vow to "give our troops the tools and equipment they need" to "defeat al Qaeda and its extremist allies."

What a difference two months make. What was grim determination then is evaporating into slippery equivocation. Some administration officials now hint at settling for something less than victory over both the Taliban and al Qaeda. And they suggest that we go for a "smaller footprint" -- not the full contingent of additional troops the commanders in the field and others back here believe we need.

What's changed since March to account for this change in strategy? For one thing, the Afghan elections did not go as well as hoped. And the administration is changing its tune about the nature of the threat -- suggesting that somehow the Taliban is not as much of a threat as al Qaeda.

The real reason, however, appears to be a bad case of cold feet. Prominent congressional Democrats are joining administration allies such as Vice President Joseph R. Biden Jr. to question the strategy approved by the president last March. Like Lyndon Johnson with respect to Vietnam, Barack Obama may be starting to adjust the military commitment to suit his domestic and political agendas.

What has not changed is America's enduring strategic interests in winning the war. This is something Mr. Obama articulated clearly in speeches before and after his election.

We still need to defeat the Taliban and deny al Qaeda and other terrorists a safe haven in Afghanistan. We still need to help create a stable government there so we can leave without having to return were the Taliban to take over again. We still need to help Pakistan secure the tribal badlands along the border and prevent al Qaeda from supporting insurgencies there and in Afghanistan.

If these goals were good in March or August, why are they questionable now? Why was it necessary to defeat the Taliban in August but too difficult to pursue that goal now?

We should remember that similarly defeatist things were said about prevailing against the insurgents in Anbar province, yet we defeated them. Gen. Stanley A. McChrystal, who led the Anbar operation, should know what is achievable better than civilian analysts in the White House. And he stated flatly that changing our counterinsurgency campaign against the Taliban and al Qaeda into a simple counterterrorism operation against al Qaeda would be a recipe for "Chaos-istan." Settling for anything less than defeating the Taliban and al Qaeda means accepting perpetual chaos in Afghanistan and trying to "manage it from outside."

The counterterrorism strategy recommended by the vice president and his allies has already failed miserably in both Afghanistan and in Iraq. The Bush administration's minimalist approach to Afghanistan focused narrowly on counterterrorism rather than counterinsurgency operations to free up military assets for the Iraq war. That allowed the Taliban to regroup across the border in Pakistan and make a violent resurgence.

The "small footprint" strategy in Iraq failed as well. Success came only when it was abandoned in favor of Gen. David Petraeus' counterinsurgency strategy, backed by the troop surge in early 2007. Even Defense Secretary Robert M. Gates has expressed skepticism about a narrower focus that relies on drones and a few special forces to defeat al Qaeda.

In considering the president's new Afghanistan strategy, watch out for false distinctions and counterintuitive arguments. They are sure signs that dissembling is about to take place. For example, when an administration official says that the Taliban is not al Qaeda, the implication is that we don't have to worry so much about the Taliban.

But of course we must worry. The Taliban still gives safe haven to al Qaeda. If they and their allies come to control more territory or the Afghan government, then those havens will expand. The issue isn't whether the Taliban and al Qaeda are identical; it's whether they are cooperating.

It's difficult to avoid the conclusion that the administration is trying to rationalize a retreat. It is one thing to adjust strategy and tactics for victory, quite another to drop the goal of victory altogether because you don't want to pay the price. That's a question of will, not strategy.

In his eagerness to justify a decision not to send more troops to Afghanistan, the president is playing one of the oldest games in the book -- defining success downward and pretending that nothing at all has changed.

But some things very real are indeed changing -- the definitions of victory and defeat.

Kim Holmes is vice president of foreign- and defense-policy studies at the Heritage Foundation and author of "Liberty's Best Hope: American Leadership for the 21st Century."