Washington ? Nearly a year after the World Trade Center and Pentagon attacks, the largest criminal probe in FBI history and a military campaign in Afghanistan costing billions, measuring success in the war against terrorism remains difficult.

The U.S.-led military campaign routed the al-Qaida terrorist network and its Taliban backers in Afghanistan, making way for a government eager to help the United States consolidate its gains against the terrorists.

An F-14 takes off from the aircraft carrier USS George Washington in the Persian Gulf. Aircraft from the carrier, responding to threats on the ground, were attacking hostile targets in Afghanistan. Since July the carrier has been operating in the region to support Operation Southern Watch, the aerial monitoring of the skies over southern Iraq, and the war in Afghanistan.

But U.S. officials remain uncertain if al-Qaida mastermind Osama bin Laden is alive or dead. And while al-Qaida clearly has been damaged, government officials and private analysts warn the organization could reconstitute itself and retains the ability to launch more attacks.

One way to think about the enemy in the war on terrorism “is like an iceberg,” says Defense Secretary Donald Rumsfeld.

“There’s a certain amount of it above the surface of the water, and then there’s a great deal going on that’s below the surface,” he said. “There’s an awful lot we don’t see.”

That makes measuring progress in this war more difficult than in a conventional conflict, where battle lines visibly ebb and flow.

Rumsfeld and many other analysts are sure the United States is winning a counterterrorism campaign that involves an unusual marriage of military, intelligence and law enforcement forces. But they warn the battle with al-Qaida and affiliated Muslim terrorist groups is far from over.

“Our enemies, without question, are sharpening their swords,” Rumsfeld said recently. “They are plotting even greater destruction, let there be no doubt.”

The military rout of the Taliban and al-Qaida in Afghanistan offers the most visible evidence the United States is prevailing, Rumsfeld and others say.

“I think we’re winning,” said Richard Perle, chairman of the Defense Policy Board. “We’re certainly not losing.”

Operating in tandem with the military campaign, law enforcement agencies around the world have smashed al-Qaida cells, arrested hundreds of operatives, thwarted attacks and tried to shut down the terrorists’ flow of funds. To date, the United States and its allies have frozen more than $112 million identified as terrorist assets.

Al-Qaida operatives are believed to have “burrowed into some 60 countries,” said Deputy Defense Secretary Paul Wolfowitz, so the job is more complicated than making war against another sovereign state.

“You don’t take it down the way you might kill a poisonous snake, by chopping off the head,” Wolfowitz said. “It’s more like an infection in the body. You have to go after the pockets of infection all over the place.”