Public Enemy No. 1

The

plan was straightforward. The CIA would help Pakistan organize a secret unit to slip into Afghanistan and snatch America's No. 1 enemy abroad: Osama bin Laden. In classic covert-action style, CIA officers would be assigned to the Pakistani infiltration team, while the U.S. would provide back-up training and equipment. President Bill Clinton signed off on the plan last year, but it never moved forward. U.S. officials now say the Pakistanis dragged their feet; the mission never got beyond basic training. "They didn't do squat," says an American familiar with the operation. More than a year after the plan was hatched, bin Laden is still at large and the special unit is defunct.

The operation, details of which TIME has uncovered, is not the only attempt to bring bin Laden to justice for allegedly masterminding the 1998 bombings of two U.S. embassies in East Africa in which more than 250 people died. The U.S. has tried everything from United Nations sanctions against Afghanistan's ruling Taleban movement for harboring bin Laden to offering $5 million for information leading to his arrest. So why--if Pakistan was reluctant to back the most serious effort to bring bin Laden to trial--did Clinton decide last week to include Islamabad on his South Asian tour? American officials are quick to tick off the reasons Pakistan matters to the U.S.: tension with India could erupt in war; like India, Pakistan recently tested nuclear weapons; the country is a transshipment point for much of the world's heroin. And there is residual hope: if the U.S. is ever going to get bin Laden, it will still need Pakistan's help.

Bin Laden is an expert at protecting himself. He supports the Taleban by providing men, money and material for the movement's fight to consolidate power in Afghanistan. "His main function over there is helping the Taleban," says a Clinton Administration official. Afghanistan's Foreign Minister Wakil Ahmad Motawakil, told TIME that bin Laden has denied involvement in the bombing of the U.S. embassies, "and we believe him." The fugitive Saudi millionaire is also taking extra precautions to remain safe. These days he travels beneath the radar, dealing directly with several lieutenants, including his de facto chief of staff Muhammed Atef, the head of Egyptian Islamic Jihad Ayman al Zawahiri and Abu Zubaydah, who is described by U.S. officials as a gatekeeper to bin Laden's training camps.

Another confidant is operations planner Abu Hafs, known in intelligence circles as "the Mauritanian" after his country of origin. U.S. counter-terror experts believe bin Laden's inner circle also includes a military-operations boss and a chief of relations with other established terrorist groups, though neither has been identified. Beyond the inner core, bin Laden attracts devotees and militants, though his links with them are not formal. Instead he stands as an ideological leader of cells in as many as 50 countries around the world. That diffusion "makes him more dangerous," says an American expert, and makes it more difficult to get at him.

Despite its close links with the Taleban, Pakistan has a strong record in supporting American counter-terrorist measures. When a gunman killed two people outside CIA headquarters in Virginia seven years ago and then fled the country, the Pakistanis eventually nabbed him on their territory and turned him over. They also arrested and extradited one of the key figures in the 1993 World Trade Center bombing in New York City, and last December Pakistan shipped to Jordan one of the ring leaders in an alleged plot to kill U.S. tourists abroad over the millennium New Year's holiday. Although Pakistan supports the Taleban, there's no love lost between Islamabad and bin Laden. His presence next door encourages Muslim extremism at home and complicates Islamabad's relations with the West.

That leaves Washington with a Pakistan dilemma: when it comes to terrorism, the country is both an ally and an occasional adversary. Like every country, it puts its perceived national interest first. As he steps off Air Force One in Islamabad on March 25, President Clinton will seek to tip that balance in America's favor.