The US National Security Agency's high-precision electronic surveillance techniques were crucial in the killing of 3,000 militants and several hundred civilians through drone attacks in Pakistan, documents leaked by Edward Snowden have shown.
The new disclosure by the Washington Post tells the story of the killing of a notorious al-Qaida operative who had unwittingly got away from the CIA dragnet, but was tracked and executed in a drone attack in Pakistan five years later.
The role of the NSA in this operation was instrumental. Vital leads in the search for Hassan Ghul, also known as Mustafa Haji Muhammad Khan, a high-profile al-Qaida operative and aide of Osama bin Laden, were unearthed by the NSA surveillance system.
The agency tapped into the emails sent by his wife and found that they contained the details needed to confirm his location. "This information enabled a capture/kill operation against an individual believed to be Hassan Ghul on October 1," one of the documents said.
Ghul was a centrepiece of the CIA's storied hunt for 9/11 mastermind bin Laden. The CIA had first got its leads to Ghul in 2003 when an al-Qaida detainee gave away his name. Ghul had escorted one of the 9/11 hijackers to a safe location in Pakistan a year before the attacks.
Later, Ghul undertook secret al-Qaeda missions in Iraq in 2003 and 2004 and was detained by Kurdish authorities there in an operation guided by the CIA. In captivity, Ghul gave away critical information that led to the killing of Osama bin Laden seven years later in Pakistan.
It was Ghul who told the CIA that bin Laden had depended on a trusted courier known as al-Kuwaiti, whose movements the agency tracked for several years to find the bin Laden hideout in Abottabad, Pakistan.
The NSA has draped a surveillance blanket over dozens of square miles of northwest Pakistan as it searched the whereabouts of militant targets, the reports said.
"In Ghul's case, the agency deployed an arsenal of cyber-espionage tools, secretly seizing control of laptops, siphoning audio files and other messages, and tracking radio transmissions to determine where Ghul might "bed down.""
The documents also reveal how a high-value al-Qaida operative like Ghul evaded the CIA's clutches. He was handed over to Pakistan in 2006 when the US administration decided to close down secret CIA prisons. He was not regarded as a dangerous or high-value source any more, and was sent to Pakistan with ostensible assurance that Islamabad would keep him in custody.
However he was a free man a year later, thanks possibly to his connections with the militant outfit Lashkar e Taiba, which had the ear of the Pakistani intelligence establishment. Once free, Ghul was instrumental in organising al-Qaida operations in the region.
Beyond the killing of Ghul in October 2012, the leaked documents give detailed account of the "intricate collaboration between the CIA and the NSA in the drone campaign," the Post said. It added that it was withholding many details of these missions at the request of US intelligence officials.
The documents revealed the agency perfected sophisticated online attack modules and was able to extract and remotely analyse vast swathes of digital information such as audio files, imagery and keystroke logs by easily plugging into suspected al-Qaida operatives' computer hard disks.
"The file is part of a collection of records in the Snowden trove that make clear that the drone campaign - often depicted as the CIA's exclusive domain - relies heavily on the NSA's ability to vacuum up enormous quantities of email, phone calls and other fragments of signals intelligence, or SIGINT," the newspaper reported.
The US government has not officially acknowledged the killing of Ghul, but the NSA did not deny the new report.
"We're focused on discovering and developing intelligence about valid foreign intelligence targets, such as terrorists, human traffickers and drug smugglers," AFP quoted NSA spokesperson Vanee Vines as saying.
"Our activities are directed against valid foreign intelligence targets in response to requirements from US leaders in order to protect the nation and its interests from threats such as terrorism and the proliferation of weapons of mass destruction."