As we begin a new year, with a new Congress being sworn in today, it's a good time to take stock of the "global war on terror." The enormous conventional military power of the United States probably ensures that we will not lose in Iraq, Afghanistan and beyond. Yet the considerable advantages of the jihadists suggest that we might not necessarily win, either.

So before we surge troops into Baghdad, as many Republicans wish, or yank everyone out of Iraq, as many Democrats are calling for, it is wise to review why America has had trouble turning wins over the Taliban and Saddam Hussein into long-term strategic successes.

Creating new political systems on the ground is far more difficult than simply blasting away terrorist concentrations. Such engagement demands that American soldiers leave the relative safety of ships, tanks and planes to fight subsequent messy battles in streets and neighborhoods. Once that happens, the United States loses its intrinsic military advantages

First, the Islamists have just enough Western arms — automatic small weapons and explosive devices — to achieve parity with individual Americans on the ground. Our billions spent on aircraft carriers, drones and stealthy jets were not intended to fight hundreds of terrorists hiding in houses.

Second, when losses mount, they are viewed differently by the two sides. Violent death and endemic poverty are commonplace in the Middle East, but not so in the West. We aim to avoid casualties in our war making; the Islamists want only to inflict them, whatever the cost to themselves.

Third, everything our soldiers do is subject to Western jurisprudence and ethical censure. Americans distinguish soldiers from civilians to avoid collateral damage. Jihadists deliberately hide among women and children to ensure that our restraint provides them sanctuary. Our utopian moral expectations can never be met; their very lack of such considerations means we are accustomed to rather than are outraged by their beheadings, kidnappings and suicide bombings.

Fourth, in the process of reconstruction, Americans are held responsible for keeping the electricity and water on to ensure that life for Afghans and Iraqis gets better. Jihadists win only by destroying such efforts. And it is always easier to tear down than to build.

So we are at an impasse. Now after five years of fighting, Americans have two stark choices in the war against terrorists.

One, we can withdraw ground troops and return to punitive and conventional bombing — tit-for-tat retaliation for each attack in the future. That way, the United States stays distant and smacks the jihadists on their home bases below. Few Americans die; terrorists sometimes do. The bored media stay more concentrated on the terrorists' provocations, not on our standoff response from 30,000 feet in the clouds.

Or American forces, at great danger, can continue to change the political and economic structure of the Middle East in hopes of fostering constitutional governments that might curb terrorism for generations. This current engagement demands our soldiers fight jihadists on their vicious turf, but by our humanitarian rules. For this, we must pay the ensuing human and materiel price — all broadcast live on the evening news.

The first choice, a return to what was practiced throughout the 1980s and 1990s, is easy and offers short-term relief with little controversy. But the second path, which we have taken to prevent another 9/11, is hard, lengthy and thus unpopular. Yet it holds out the promise of long-term solutions in Afghanistan and Iraq.

Presidents Reagan, Bush senior and Clinton, who respectively skedaddled out of Beirut, skipped Baghdad and fled from Mogadishu, didn't risk, lose or solve much against the terrorists.

In contrast, George W. Bush wagered everything by going into Afghanistan and Iraq. And he will either make things much worse or much better for millions — depending on how successfully the United States can endure the messy type of war that jihadists welcome and the American military usually seeks to avoid.

Military success on the ground now demands that we expand the rules of engagement to allow our troops to shoot more of the jihadists, disarm the militias, train even more Iraqis troops to take over security more quickly, and seal the Syrian and Iranian borders.

This solution, of course, is easier said than done. The military must use more force against those who are destroying Iraqi democracy at precisely the time the American public has become exasperated with both the length and human cost of the war.

Imagine this war as a sort of grotesque race. The jihadists and sectarians win if they can kill enough Americans to demoralize us enough that we flee before Iraqis and Afghans stabilize their newfound freedom. They lose if they can't. Prosperity, security and liberty are the death knell to radical Islam. It's that elemental.

Victor Davis Hanson is a classicist and historian at the Hoover Institution at Stanford University. You can reach him by e-mailing author@victorhanson.com.