President Bush has been back from the Asian subcontinent for more than a week now, but one big question from his trip remains: How did it happen that the president spent a night in Pakistan, the assumed haven of Osama bin Laden and one of the one most dangerous countries in the world?

The short answer is that Pakistan's president, Pervez Musharraf, insisted. The long answer is a tale about the nightmares of the Secret Service and the calculated risks of presidential travel.

For Mr. Bush, who also kept the Secret Service busy with a stop in Kabul, the story began in January, when he met with Pakistan's prime minister, Shaukat Aziz, in the Oval Office. It was then, an administration official said, that Mr. Bush privately committed to the overnight stay in Pakistan. After the meeting, Mr. Bush announced that he would be visiting Pakistan and India in March, but White House officials left the dates for Pakistan vague. They repeatedly refused to say when, or for how long, Mr. Bush would be in the country.

The fuzziness was to keep terrorists guessing about the timing of motorcades and the arrival of Air Force One, basic precautions passed down from a cloak-and-dagger trip that President Bill Clinton made to Pakistan in 2000 that had the Secret Service in an uproar. Six years later, accounts of the trip from former Clinton administration officials are far more harrowing than was known at the time.