AFGHANISTAN-PAKISTAN BORDER — The al-Qaida terror camps are gone from Afghanistan, but the enigma of Osama bin Laden still hangs over these lawless borderlands where tens of thousands of U.S. and Pakistani troops have spent nearly five years searching for him.

Villagers say the CIA missed by only a few miles when it targeted bin Laden's top deputy, Ayman al-Zawahri, with a missile strike in January. Then in May, U.S. Special Forces arrested one of al-Zawahri's closest aides, suggesting the trail has not gone entirely cold.

As for bin Laden himself? He may be nearby. Yet hopes of cornering the Saudi-born al-Qaida leader seem distant as ever. The last time authorities said they were close to getting him was in 2004, and in hindsight those statements seem more hope than fact.

Five years after the Sept. 11 attacks, the most publicized manhunt in history has drawn a blank. The CIA has dismantled its unit dedicated to finding the al-Qaida chiefs. And the American military's once-singular focus is diffused by the need for reconstruction and a growing fight against the Taliban, the resurgent Afghan Islamic movement that once hosted bin Laden.

American soldiers climbing through the forested mountains of Afghanistan's Kunar province — where in the 1980s bin Laden fought in the U.S.-backed jihad against the Soviets — still hope to catch or kill him. But they say bolstering the Afghan government is their primary mission now, amid the worst upsurge in Taliban attacks in five years.

"It is like chasing ghosts up there," said Sgt. George Williams, 37, of Watertown, N.Y., part of the Army's 10th Mountain Division pushing into untamed territory along the border with Pakistan. "Osama bin Laden is always going to be a target of ours as long as he is out there, but there are other missions: to rebuild Afghanistan and attack the militants still here."

The top leaders of al-Qaida remain free despite more than 100,000 U.S., Afghan and Pakistani forces at the frontier. High-tech listening posts, satellite imagery, unmanned spy planes — not to mention a $25 million bounty on each man from the U.S. government — all aid the hunt.

Yet both bin Laden and al-Zawahri are communicating to the outside world, posting messages on Islamic Web sites to inspire further attacks on the West. Although the al-Qaida leaders are too isolated to run directly a terrorist operation like Sept. 11, Pakistan says the latest alleged plot, to bomb U.S.-bound jetliners from Britain, may have been blessed by al-Zawahri.

The frustrating campaign has frayed critical cooperation between Afghanistan and Pakistan, neighbors separated by an ill-defined frontier and a history of mutual suspicion.