After the 2009 phone call that the Pakistanis tapped, however, al Kuwaiti's number went dark. But the courier had exposed himself, and the CIA suspected that if they could find where al Kuwaiti lived, they might be about to find bin Laden.
The call had located al Kuwaiti in northwest Pakistan and gave the CIA a starting point for a renewed hunt. A year later, in the summer of 2010, despite fastidious operational security by al Kuwaiti -- he normally drove 90 minutes from the compound before inserting the battery in his cellphone, preventing signals intelligence pinpointing his starting point – he made a twofold mistake. For the first time in almost a year, he used the cellphone simcard that U.S. intelligence had linked to him, and he made a call with that simcard close to bin Laden's compound.
The National Security Agency, the world's most powerful signals intelligence organization, had been waiting to pounce on any calls made from that simcard since 2009. The NSA picked up the call and located al Kuwaiti in Abbottabad, Pakistan. They were even able to pinpoint the neighborhood the call had probably come from. From there, the CIA and National Geospatial-Intelligence Agency (NGA) began searching aerial satellite photographs to deduce which house would likely be bin Laden's.
When they discovered a newer building with high perimeter walls, custom construction and a third floor terrace wall of seven feet--the CIA knew they had their target. The search was almost over.
By August of 2010, CIA director Leon Panetta briefed President Obama and had a new stealth drone begin flights over the compound, undetected by Pakistani air defenses. The CIA was sure a high-value target lived in the compound, and given al Kuwaiti's relationship to bin Laden--learned in bits and pieces from interrogations of captured detainees since 2002 -- was "60 to 80 percent" sure bin Laden was hiding in the compound, according to Panetta.
The CIA, the NGA and the Pentagon studied reams of signals intelligence, electronic emissions, infrared technology, almost all from drones and satellites, in order to learn the compound's construction and the number of people living inside. Intelligence analysts even studied the water tables underneath the Abbottabad valley to determine whether it was likely bin Laden had built an escape tunnel underneath the house.
"We were pretty sure it was too wet to build a tunnel," one US official familiar with the CIA's intelligence said.
Martin, the retired CIA official, said bin Laden also undoubtedly learned from his al Qaeda operatives' mistakes.
"He was not stupid. If you see your men killed by drones or captured, you learn from experience what kind of entourage to have and how to change your profile."
Bin Laden had taken away all signs of his importance that for years the CIA had searched for from the sky: armed guards, rings of protection, transportation convoys -- he left it all behind and hid behind an 18-foot wall for five years. When the Navy SEALs eventually stormed the compound, only a few rifles and handguns were seized. He had dropped virtually all his protection so that spy satellites, and drone surveillance would be unable to differentiate his compound from any other in the area. The SEALs also found, and killed, the courier whose single errant phone call, snapped up in a web of electronic surveillance, had led them to Abbottabad.