He witnessed his nation humiliated in war. He vowed it would never happen again.

Carl von Clausewitz served as the young aide-de-camp to Prince August Ferdinand of Prussia. At the battles of Jena-Auerstedt (1806), he stood by as Napoleon's forces obliterated the once-proud legions of Frederick the Great.

Branded by defeat, Clausewitz dedicated his career to reforming the Prussian army. He rose to the rank of major general and commanded the war academy. His greatest accomplishment was authoring "On War," the most widely studied tome on military theory in the Western world. [Warning: It is also one of the most difficult reads.]

One of Clausewitz's most famous maxims was that war was "merely the continuation of politics by other means." Scholars still debate what he meant by that. All we know for sure is what he did not mean -- that leaders should play politics with their wars.

Washington is a very un-Clausewitzian place. Politicians want to treat the war in Afghanistan as just another political debate.

That means throwing every argument imaginable in opposition to the war no matter how nonsensical. The latest show of stupidity is that the United States needs to cut and run in the face of al Qaeda because America can't afford to fight.

Arguing that war costs are unbearable and sinking the economy is like contending that the prices of bread and milk are breaking the family budget. The burden of "providing for the common defense" (unlike most federal spending) is required by the Constitution> -- and defense spending is not what is emptying the bank.

The defense budget is less than 4 percent of gross domestic product, only about half of what America spent on average during the Cold War. Today, Pentagon spending accounts for less than one-fifth of the federal budget.

As for total government spending, national defense ranks a distant fourth, trailing financial support for the elderly (through Social Security and Medicare), education funding and means-tested welfare payments.

Opponents of the war on terrorism have resurrected the argument that it's too expensive to win wars. In "The Three Trillion Dollar War," for example, Joseph Stiglitz went postal over war costs in Iraq.

Fortunately, former President George W. Bush didn't buy that argument. Instead, he authorized a surge that turned the course of the war.

Howls that "defense costs too much" ring even hollower today. Within the last year, Congress has eagerly showered checks for hundreds of billions of dollars on dicey financial gambits like the Troubled Asset Relief Program or the demonstrably nonstimulating "stimulus package."

At the same time, political leaders are pushing for new multitrillion-dollar health care and cap-and-trade programs.

Compared with those tabs, military spending (including the costs of all the battles in the global war on terrorism) looks pretty darn modest. The way we are going, the federal debt will be $4.8 trillion in just five years. By then, the interest payment on the debt alone will exceed the entire defense budget.

If opponents of winning in Afghanistan were really concerned about pulling our economy back from the abyss, they would address the fiscal irresponsibility in Washington that lets spending run wild and hamstrings Americans with more taxes.

That, however, is not what this debate is all about. When Sen. Carl Levin, D-Mich., suggested that if more troops were needed in Afghanistan the rich should be taxed to pay for it, he was just trying to stir up more animosity, pitting one group of Americans against another. Such tactics may be clever politics ... but it's no way to fight a war.

The blunt truth is: The United States needs to win in Afghanistan. Defeating the Taliban and destroying al Qaeda is in our vital interests. It is the price of peace in South Asia. It is the only way to prevent another 9/11.

By dedicating the resources needed to win and by getting our fiscal house in order, we can keep our nation safe, free and prosperous. Any other talk is just politics.

James Jay Carafano, Ph.D., is Assistant Director of the Kathryn and Shelby Cullom Davis Institute for International Studies and Senior Research Fellow for National Security and Homeland Security in the Douglas and Sarah Allison Center for Foreign Policy Studies at The Heritage Foundation.