Disclosures put US on defensive about extent of its eavesdropping

An avalanche of intelligence leaks from former CIA contractor Edward Snowden sent shockwaves around the world in 2013, lifting the lid on a vast global spying network and raising fears of a surveillance state.

As the year draws to a close, the 30-year-old Snowden remains exiled in Russia, his final port of call following a worldwide game of cat-and-mouse that appeared to come straight from the pages of a spy novel.

A traitor to some, a heroic whistle-blower to others, Snowden's disclosures have shed light on intelligence-gathering methods which shocked many through their sheer scale.

Tens of thousands of documents leaked by Snowden to The Guardian newspaper and other media outlets have detailed the nature of the National Security Agency's hitherto shadowy activities.

The fugitive Snowden, Time magazine's runner-up behind Pope Francis for its person of the year, told the magazine he hoped the leaks would lead to greater transparency on the part of governments.

"What we recoil most strongly against is not that such surveillance can theoretically occur, but that it was done without a majority of society even being aware it was possible," he said via e-mail in a rare interview.

Snowden's revelations showed that metadata and information from millions of e-mails and phone calls - incidentally, some of it about US citizens - has been systematically raked in by the NSA.

Civil rights groups decried the NSA's activities as the actions of a Big Brother-like government, trampling on the rights of individuals with little oversight.

The repercussions have been felt far and wide. US President Barack Obama in August promised reforms to improve "transparency" while at the same time stating that many of the NSA programs were a necessity.

Washington has also had to soothe the anger of its allies, particularly after revelations that the NSA had targeted German Chancellor Angela Merkel's phone.

Yet according to some analysts, the long-term consequences of the Snowden revelations remain to be seen.

James Lewis, an expert in technology and public policy at the Center for Strategic and International Studies in Washington, questioned whether there would be a fundamental change in the practices of the intelligence community.

"You're not going to see major changes," said Lewis, estimating that opponents of the programs remained a "noisy minority" of around 20-25 percent of voters.

"I think the majority of the American people would rather see programs that are more transparent and have greater oversight in exchange for smaller risk of attack," he said.

Lewis believes the problem is that "people have never appreciated the difference between collect and read".

"Nobody can sit down and read 70 million e-mails but you could get machines to identify those with links to terrorism or proliferation," he said.

One of the programs set up under the 2001 Patriot Act allows for the collection from US phone companies of metadata, such as numbers called and the time and duration of calls.

The gathering of such data from ordinary US citizen sparked outrage in the US and led Congress to try to rein in the NSA.

Gordon Adams, an expert on defense and national security at American University, says the NSA was given unprecedented freedom following the Sept 11, 2001 attacks.

"In a climate of fear we basically took the reins off of accountability for the intelligence community," Adams said.