Phone call led U.S. to bin Laden compound

WASHINGTON - It seemed an innocuous, catch-up phone call. Last year, Abu Ahmed al-Kuwaiti, the pseudonym for a Pakistani known to U.S. intelligence as the main courier for Osama bin Laden, took a call from an old friend.

"Where have you been?" inquired the friend. "We've missed you. What's going on in your life? And what are you doing now?" Al-Kuwaiti's response was vague but heavy with portent: "I'm back with the people I was with before."

There was a pause, as if the friend knew that al-Kuwaiti's words meant he had returned to bin Laden's inner circle, and was perhaps at the side of the al-Qaida leader himself.

"May God facilitate," the friend replied.

When U.S. intelligence officials learned of this exchange, they knew they had reached a key moment in their decade-long search for al-Qaida's founder. The call led them to the unusual, high-walled compound in Abbottabad, a city 35 miles north of Pakistan's capital.

"This is where you start the movie about the hunt for bin Laden," said one U.S. official briefed on the intelligence-gathering leading up to the raid on the compound.

Gave Obama confidence

The exchange and several other pieces of information, other officials said, gave President Barack Obama the confidence to launch a politically risky mission to capture or kill bin Laden, a decision he took despite dissension among his key national security advisers and varying estimates of the likelihood that bin Laden was in the compound.

The officials would speak about the collection of intelligence and White House decision-making only on the condition that they not be named.

U.S. intelligence agencies had been hunting for al-Kuwaiti for at least four years. The call with the friend gave them the number of the courier's cellphone. Using a vast number of human and technical sources, they tracked al-Kuwaiti to the compound.

The main three-story building, which had no telephone lines or Internet service, was impenetrable to eavesdropping technology deployed by the National Security Agency.

U.S. officials were stunned to realize that whenever al-Kuwaiti or others left the compound to make a call, they drove some 90 minutes away before even placing a battery in a cellphone. Turning on the phone made it susceptible to the kind of electronic surveillance that the residents of the compound clearly wished to avoid.

As intelligence officials scrutinized images of the compound, they saw that a man emerged most days to stroll the grounds of the courtyard for an hour or two. The man walked back and forth, day after day, and soon analysts began calling him "the pacer." The imagery never provided a clear view of his face.

Intelligence officials were reluctant to bring in other means of technical or human surveillance that might offer a positive identification but would risk detection by those in the compound. The pacer never left the compound.

Was he bin Laden? A decoy? Bin Laden was at least 6-foot-4 and the pacer seemed to have the gait of a tall man. The White House asked the National Geospatial-Intelligence Agency, which provides and analyzes satellite imagery, to determine the pacer's height. The agency estimated between 5-foot-8 and 6-foot-8, said one official.

In one White House meeting, CIA Director Leon Panetta told Obama that those tracking the compound were seeing the pacer nearly every day but could not conclude with certainty that it was bin Laden, officials said. Panetta noted that it was too risky to send in a human spy or move any closer with electronic devices. The Washington Post reported last week that the agency established a safe house in Abbottabad for a small team that monitored the compound in the months leading up to the raid.

Panetta designated Navy Vice Adm. William McRaven, who had headed the Joint Special Operations Command for nearly three years, to devise a boots-on-the ground plan for the special forces that became known as "the McRaven option." McRaven had increased the intensity of Special Operations raids, especially in Afghanistan. During his first two years as head of the Special Operations Command, the "jackpot rate" -- when the strikes got their intended target -- jumped from 35 percent to more than 80 percent.

Life in compound studied

A "pattern of life" study of the compound by intelligence agencies showed that about a dozen women and children periodically frequented it.

Specific orders were issued to the SEALs not to shoot the women or children unless they were clearly threatening or had weapons. Bin Laden was to be captured, one official said, if he "conspicuously surrendered."

The longer such raids take, the greater the risk to the SEALs. One senior official said the general philosophy of the SEALs is: "If you see it, shoot it. It is a house full of bad guys."

Several assessments concluded there was a 60 percent to 80 percent chance that bin Laden was in the compound. Michael Leiter, the head of the National Counterterrorism Center, was much more conservative. During one White House meeting, his guess was about 40 percent.

When a participant suggested that was a low chance of success, Leiter said, "Yes, but what we've got is 38 percent better than we have ever had before."

Officials said Obama's national security advisers were not unanimously for the McRaven option. Still, the president approved the raid at 8:20 a.m. Friday.

In the White House Situation Room on Sunday night, the president and his national security team watched a soundless video feed of the raid.

When bin Laden's corpse was laid out, one of the Navy SEALs was asked to stretch out next to it to compare heights. The SEAL was 6 feet tall. The body was several inches taller.

After the information was relayed to Obama, he turned to his advisers and said: "We donated a $60 million helicopter to this operation. Could we not afford to buy a tape measure?"