August 17, 2009 - Much has been done in six months to deal with the ongoing war in Afghanistan. We have restated that our aim is to eliminate the threat of Al Qaeda; built a new leadership team, including Special Representative Richard Holbrooke; reinforced our troop strength and adjusted our tactics; and have begun augmenting our force with synchronized diplomatic, political and economic efforts.

But can we explain how all of this adds up to an effective strategy that will sustain American engagement in one of the world's least accessible regions?

The American people are growing increasingly wary. In a new CNN/Opinion research poll, fully 54% of respondents now say they oppose the U.S.-led fight against the Taliban and their Al Qaeda allies. Those are striking numbers, and a serious warning to the Obama administration.

The difficulty here lies less in PowerPoint presentations and more in the complexities of the war itself. Our real enemy, Al Qaeda, may now be more entrenched in Pakistan than in Afghanistan. Taking the fight directly into Pakistan with ground forces risks expanding the conflict and undercutting a fragile Pakistani civilian government.

The similarities to Vietnam are ominous. There, too, an insurgency was led and supported from outside the borders of the state in which our troops were fighting. There, too, sanctuaries across international borders stymied U.S. military efforts. There, too, broader political-strategic considerations weighed against military expansion of the conflict and forecast further struggles in the region.

And there, too, American public support slid away over time as our engagement ratcheted up and casualties mounted.

Our Vietnam experiences provide powerful lessons in how to explain strategy and retain public support, so we can ultimately succeed.

First, we must maintain a clear and unwavering purpose - and not overstate our accomplishments. In Vietnam, we seemed to change our objectives whenever they were seriously challenged. At one time or another we fought to halt Communist aggression from the North, to avoid the fall of the "Southeast Asian dominoes," to prevent a slaughter should the Viet Cong take over, and to maintain U.S. "credibility." And we kept promising "light at the end of the tunnel," until Tet shattered public expectations and support.

So in Afghanistan, we must avoid confusing Americans by citing too many justifications for our presence. We aren't there to create democracy for Afghans, stabilize a nuclear-armed Pakistan or deal with strategic rivalry on the subcontinent. These may be means to an end, but we must not lose public focus on Al Qaeda. And we must be cautious in claiming progress.

Second, we must realize that, as we ratchet up our military commitment against the insurgency in Afghanistan, we will take increased losses, and this will limit our political staying power. We must get the balance right between the urgency of the mission and the costs and risks of actions to speed up our success. In Vietnam it turned out there were actually extraordinary military measures that might have been decisive against the North, but we were self-deterred from taking them until it was too late. We should have gone after the North by air more heavily sooner; we should have cut off their base areas in Cambodia and Laos sooner and more effectively.

Our military must seek to find more effective measures against the enemy headquarters and base areas in Pakistan - and the Predator strikes are a good start. Let's not wait too long to act.

Finally, we gain nothing by blaming our hosts or their culture. In Vietnam, we constantly complained about the ineffectiveness of our allies and engineered the ouster of South Vietnamese leaders. In the end, we simply ended up owning the problem. In Southwest Asia today, Americans must recognize that local leaders and their institutions do not share our own priorities and values. We cannot really build a nation for other people, and the American public must not expect it. Instead we will be working quietly behind the scenes to focus greater regional efforts against Al Qaeda.

Our commitment to defeating Al Qaeda need be nothing like our tragedy in Vietnam - unless we make it so. Under the Obama administration, we are off to a good start. Let's learn from America's errors, not relive them.

Clark is a former supreme commander of NATO, led the alliance of military forces in the Kosovo war (1999) and is a senior fellow at the Ron Burkle Center at UCLA.

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