WASHINGTON -- The day before he suffered a fatal tear in his heart last December, a frustrated Richard Holbrooke confided to a colleague: The Obama administration had tried everything to convince Pakistan to crack down on terrorism, including threats and special-assistance packages, but none of it seemed to work. Why wasn't Pakistan getting the message?

The question posed by Holbrooke in his final hours as U.S. representative for Afghanistan and Pakistan looms even larger now. Despite years of American requests that Pakistan dismantle al-Qaeda and its allies, it turns out that Osama bin Laden had been hiding for six years near a military training academy two hours north of Islamabad.

A catalogue of these U.S. pleas, assembled from interviews with knowledgeable officials, makes disturbing reading. Washington has been passing the same message, through two administrations: The Pakistani military promises action, but hedges its bets; the U.S. pledges cooperation, but acts unilaterally. As the problem festers, mutual mistrust increases.

The story moves inexorably toward the U.S. raid on bin Laden's compound, which ripped the veneer of cooperation. Repairing relations in the aftermath would require a degree of honesty and partnership that neither side seems able to muster. One key policymaker grimly predicts: "This comes to a bad end."

Let's start with the final months of the Bush administration: A sharp warning was delivered July 12, 2008, in Islamabad by Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, and Stephen R. Kappes, then deputy director of the CIA. The two warned that Sirajuddin Haqqani, a Taliban leader with links to Pakistani intelligence, knew about the activities of Arabs in al-Qaeda. They issued a similar warning about Maulvi Nazir, a warlord in the Pakistani tribal areas who the U.S. believed had connections to both al-Qaeda and Pakistan's Inter-Services Intelligence directorate.

Pakistani officials assured the American visitors that the Haqqani network "will not be provided with any support by any agency of Pakistan," a source recalls. But U.S. officials believe the Haqqani network's contacts with ISI continued. It remains the deadliest insurgent group in eastern Afghanistan.