Classified documents published Thursday by The Washington Post reveal new details about the U.S. operation that killed Osama bin Laden in 2011. (Rahimullah
Classified documents published Thursday by The Washington Post reveal new details about the U.S. operation that killed Osama bin Laden in 2011. (Rahimullah Yousafzai/AP)

WASHINGTON — The U.S. commando raid that killed Osama bin Laden was guided from space by a fleet of satellites, which aimed dozens of separate receivers over Pakistan to collect a torrent of electronic and signals intelligence as the mission unfolded, according to a top-secret U.S. intelligence document.

The National Security Agency was also able to penetrate guarded communications among al-Qaida operatives by tracking calls from mobile phones identified by specific calling patterns, the document shows. Analysts from the Central Intelligence Agency pinpointed the geographic location of one of the phones and tied it to the compound in Abbottabad, Pakistan, where an accumulation of other evidence suggested bin Laden was hiding.

The new disclosures about the hunt for bin Laden are contained in classified documents that detail this year's "black budget" for U.S. intelligence agencies, including the NSA and CIA. The documents, provided to The Washington Post by former NSA contractor Edward Snowden, make only brief references to the bin Laden operation. But the mission is portrayed as a singular example of counter-terrorism cooperation among the U.S. government's numerous intelligence agencies.

Eight hours after the raid, according to the documents, a forensic intelligence laboratory run by the Defense Intelligence Agency in Afghanistan had analyzed DNA from bin Laden's corpse and "provided a conclusive match" confirming his identity. The budget further reveals that satellites operated by the National Reconnaissance Office performed over 387 "collects" of high-resolution and infrared images of the Abbottabad compound in the month prior to the raid — intelligence that was "critical to prepare for the mission and contributed to the decision to approve execution."

Also playing a role in the search for bin Laden was an arm of the NSA known as the Tailored Access Operations group. Among other functions, Tailored Access Operations specializes in surreptitiously installing spyware and tracking devices on targeted computers and mobile phone networks.

Although the budget does not provide detail, it reports that Tailored Access Operations "implants" enabled the NSA to collect intelligence from mobile phones that were used by al-Qaida operatives and other "persons of interest" in the bin Laden hunt.

Separately, Tailored Access Operations were used in April 2011, the month before bin Laden was killed, when U.S. Forces in Afghanistan relied on signals intelligence from implants to capture 40 low- and mid-level Taliban fighters and other insurgents in that country, according to the documents.

The new details about the bin Laden raid fill out an already rich public account of how the U.S. government employed virtually every tool in its enormous surveillance apparatus to locate the elusive founder of al-Qaida. For more than a decade, bin Laden stymied all efforts to find him by making certain he did not leave a direct electronic trail. He steadfastly avoided phones and email, relying on face-to-face communications with a small number of couriers and middlemen.

In addition to the satellites, the government flew an advanced stealth drone, the RQ-170, over Pakistan to eavesdrop on electronic transmissions. The CIA also recruited a Pakistani doctor and other public health workers to try to obtain blood samples from people living in the Abbottabad compound as part of a vaccination program to determine if the residents might be related to bin Laden.

For all their technological prowess, U.S. spy agencies failed to identify its target with confidence inside the Abbottabad compound. By the time President Barack Obama ordered a team of Navy SEALs to storm the site in May 2011, U.S. intelligence officials told the president that, according to their best guesses, the odds that bin Laden was present were between 40 and 60 percent.

Even after bin Laden's death, however, the U.S. government kept up its relentless high-tech campaign to unlock his secrets.

Budget documents show that intelligence agencies scraped together $2.5 million in emergency funds in September 2011 to sift through a backlog of computer files and other evidence recovered from bin Laden's hideout. The money went to buy 36 computer workstations and pay overtime to forensic examiners, linguists and "triage personnel" involved in the project.