Intelligence officials refer to Edward Snowden's job as a National Security Agency contractor as "systems administrator" - a bland name for the specialists who keep the computers humming. But his last job before leaking classified documents about NSA surveillance, he told The Guardian , was actually "infrastructure analyst". It is a title officials have avoided mentioning, perhaps for fear of inviting questions about the agency's aggressive tactics: an infrastructure analyst at the NSA, like a burglar casing an apartment building, looks for new ways to break into internet and phone traffic around the world. That assignment helps explain how Snowden got hold of documents laying bare the top-secret capabilities of the nation's largest intelligence agency, setting off a far-reaching political and diplomatic crisis for the Obama administration. Some congressmen have challenged the NSA's collection of logs of nearly every phone call Americans make, and European officials have protested furiously after Snowden's disclosure that the NSA has bugged European Union offices in Washington and Brussels and, with its British counterpart, tapped the continent's major fibre-optic communications cables. Snowden, who planned his leaks for at least a year, has said he took the infrastructure analyst position with Booz Allen Hamilton in Hawaii in March, evidently taking a pay cut, to gain access to a fresh supply of documents. "My position with Booz Allen Hamilton granted me access to lists of machines all over the world the NSA hacked," he told the South China Morning Post before leaving Hong Kong for Moscow, where he has been in limbo in the transit area of Sheremetyevo Airport. "That is why I accepted that position about three months ago." Collecting an ocean of internet data requires the brazen efforts of tens of thousands of technicians like Snowden. US President Barack Obama played down Snowden's importance, perhaps concerned the manhunt was damaging the image and diplomatic relations of the US. "No, I'm not going to be scrambling jets to get a 29-year-old hacker," he said during a stop in Senegal. Obama presumably meant the term to be dismissive, suggesting that Snowden - who turned 30 on June 21 - was a young computer delinquent. But as an NSA infrastructure analyst, Snowden was, in a sense, part of the United States' biggest and most skilled team of hackers. The NSA, Snowden's documents show, has worked with its British counterpart, Government Communications Headquarters, to tap into hundreds of fibre-optic cables that cross the Atlantic or go on into Europe. The disclosure revived old concerns that the British might be helping the NSA evade American privacy protections, an accusation American officials flatly deny. And a secret presidential directive on cyberactivities unveiled by Snowden - discussing the primary new task of the NSA and its military counterpart, Cyber Command - makes clear that when the agency's technicians probe for vulnerabilities to collect intelligence, they also study foreign communications and computer systems to identify potential targets for a future cyberwar. Infrastructure analysts like Snowden, in other words, are not just looking for electronic back doors into Chinese computers or Iranian mobile networks to steal secrets. They have a new double purpose: building a target list in case American leaders in a future conflict want to wipe out the computers' hard drives or shut down the phone system. The NSA's assessment of Snowden's case will likely also consider what has become, for intelligence officials, a chilling consideration: there are thousands of people of his generation and computer skills at the agency, hired to keep up with the communications boom. The officials fear some of them, like young computer aficionados outside the agency, might share Snowden's professed libertarian streak and scepticism of the government's secret power.