When al-Qaida struck the United States on Sept. 11, Osama Bin Laden was far away in Afghanistan, safe in a hideout. Others killed and died for him. He hit us, but we couldn't hit him.

When the United States set out to punish Bin Laden, he hid behind the Taliban. Al-Qaida deserted its training camps, leaving U.S. pilots no obvious targets. On video, Bin Laden sat with a rifle and boasted of filling Americans with fear. In reality, he remained underground, leaving Afghan soldiers to kill and die for him. He had hit us, but we couldn't hit him.

At a Pentagon briefing a week after the Sept. 11 attacks, U.S. Defense Secretary Donald Rumsfeld explained the asymmetry at the heart of Bin Laden's strategy. Offensively, al-Qaida could hit the United States by targeting civilians rather than taking on the U.S. armed forces. Defensively, al-Qaida leaders could avoid retaliation by concealing their identities or locations. "In the past, we were used to dealing with armies and navies and air forces and ships and guns and tanks and planes," said Rumsfeld. "This adversary is different. It does not have any of those things. It does not have high-value targets that we can go after."

Logic seemed to dictate that if we couldn't get Bin Laden from the air, we would have to send in ground troops. "If Bin Laden hides in that hole that the president talked about, to smoke him out requires men on the ground," ABC's Sam Donaldson suggested in a Sept. 16 interview. Rumsfeld replied in the affirmative. "Cruise missiles do not get people who are operating in the shadows," he observed.

Bin Laden figured that once the United States put men on the ground, the asymmetry would move to Afghanistan. He and his deputies would hide in caves while their Taliban protectors fired on American soldiers. "The fate of the United States will be worse than Russia," a Taliban commander boasted. "Our real war will begin the day the U.S. troops would land in Afghanistan."

But the joke was on Bin Laden. The asymmetry Rumsfeld brought to Afghanistan was upside-down. American planes rained destruction from beyond the Taliban's reach. Some strikes killed al-Qaida officers, including Bin Laden's chief military operative. The men who battled the Taliban on the ground weren't Americans, but Afghans of the Northern Alliance. We could hit Bin Laden's men, but he couldn't hit us.

Now comes the punch line. With the Taliban's grip broken and Bin Laden on the run, the United States is coming for his head. He'd like our infantrymen to make themselves easy targets for Taliban guerrillas by marching into the mountains to find him. No such luck. Yesterday, Rumsfeld offered a $25 million reward for information leading to Bin Laden's death or capture. Some enterprising Afghan warlord with a good network will do the job. We'll hit Bin Laden for the last time, and he can't hit us.

None of this guarantees our safety at home. Al-Qaida or another terrorist organization could strike the United States tomorrow. But now Bin Laden understands, too late, that asymmetry can go both ways. If that isn't perfect justice, imperfect symmetry will do.