When Edward Snowden announced to The Guardian's Glenn Greenwald, and through Greenwald, the world, that he was the National Security Agency leaker behind a trove of top secret U.S. documents, he justified pilfering the documents as a way to inform American citizens about what he sees as an invasive, broad, possibly unconstitutional overreach by the U.S. spy agency.

That message fits with Greenwald's own strongly held (and frequently voiced) views about the erosion of American civil liberties. And it fit the first few articles based on Snowden's leaks. The NSA's massive collecting of U.S. phone records, and the nebulous PRISM program to gather court-approved customer data from internet companies (and other electronic-data processing firms).

But since then, the American public has been conspicuously absent from Snowden's leaks. He talked to a Hong Kong newspaper about U.S. hacking of Chinese servers, then fed a Guardian story about British intelligence spying on foreign leaders and diplomats at a 2009 G20 summit, with only a tangential aside about the NSA.

In some ways, this foreign focus makes sense — the NSA is supposed to be aimed at foreign intelligence, and isn't legally allowed to eavesdrop on American citizens except in extreme, court-approved circumstances where national security is at stake.

So, just what exactly is Snowden's goal in leaking classified U.S. secrets? Probably nobody but Snowden actually knows. But there are a lot of theories. A look at six of the most interesting:

1. Snowden is a traitor, and possibly a Chinese spy
The argument over whether Snowden is a hero or traitor dates back to the minutes after The Guardian posted the self-outing video, and the suspicion that he's a spy for China was raised not long after. Last week, the top Republican and Democrat on the House Intelligence Committee posed the idea that Snowden had unknown ties to China that needed further investigation, and former Vice President Dick Cheney was more direct on Sunday.

Snowden is a "traitor" who has endangered U.S. national security, Cheney said on Fox News Sunday. Cheney added that he is "deeply suspicious" that Snowden is a Chinese agent, and might have had help from inside the NSA. Watch:

Snowden as a Chinese agent isn't as wildly conspiratorial as it may sound, says Toby Harnden at Real Clear Politics. After all, he "began working for Booz Allen Hamilton only after he had contacted reporters, suggesting he might have been directed to Hong Kong by someone or have gone there for a specific purpose." Then there's the timing of his leaks — when President Obama was meeting with China's new president — and the fact that his NSA station in Hawaii "conducts cyberoperations against China and North Korea, making the island a priority for Chinese intelligence," Harnden says.

Frank Snepp, a former dissident CIA agent, tells Harnden he was "stunned" when Snowden started spilling NSA secrets to the Chinese press. It could be because Snowden is disoriented, Snepp says, but "the old spook in me is inclined to look for other reasons than the ones he articulates and one obvious reason is he's a very good catch for the people who run Chinese intelligence in Hong Kong." And if he isn't a Chinese agent yet, Snepp adds, being branded a traitor by Congress means "there's a very good chance he could begin naming names."

For the record, China's foreign ministry denies that Snowden is a Chinese spy or cooperating with China. The charge is "utterly ridiculous," ministry spokeswoman Hua Chunying said on Monday. Snowden also addressed the charge in an interview with the South China Morning Post last week, telling the Hong Kong paper: "I'm neither traitor nor hero. I'm an American."

2. He appears to be opposed to spying, period
The common thread in Snowden's leaks and public statements is a push to expose U.S. government surveillance (and, it appears, British eavesdropping, too). He has at various points explained this as revealing hypocrisy, protecting the Constitutions and U.S. civil liberties, or trying to spark a discussion about the proper role of government, but it increasingly looks like "Snowden's problem is larger than domestic spycraft," says David Weigel at Slate. "It's a problem with spycraft, period."

Joshua Foust, a journalist who's been critical of The Guardian's reporting, has similar concerns:

3. Snowden wants to save the world from America
While most of Snowden's comments have been focused on the U.S., he has also expressed concerns about the NSA's activities abroad, as they affect average citizens of other countries. It's possible that he is sincere about trying "to help the public of the world, regardless of whether that public is American, European, or Asian," as he told the South China Morning Post, or keep the U.S. government from destroying "privacy, internet freedom, and basic liberties for people around the world," as he told The Guardian.

4. He wants to be a martyr
"The desire for martyrdom — and for the long-lasting fame that sometimes comes with it — is common to all cultures," says Anne Applebaum at Slate. And from his public comments, "certainly Snowden styles himself a martyr," detailing all he has given up to to protect liberty. But by talking to the press, repeatedly, it's clear "his interest in publicity trumps his stated fear of arrest."

Nothing about the context, in other words, tells us that Snowden is interested in anything other than martyrdom and a perverse sort of fame. Nothing tells us that his primary interest is the welfare of his fellow Americans. Nothing about his actions, so far, seems likely to help him achieve his stated goals.... Unless we learn something new, the NSA's data-mining will not come to a halt because of Snowden's personal sacrifice — and, at the moment, it doesn't seem likely that anyone will build a cathedral in his honor.

The Guardian has called his leak "the spy story of the age." But the mere impulse to martyrdom is not in and of itself evidence of wisdom. Nor is it evidence of the righteousness of the martyr's cause. [Slate]

5. He might be an NSA plant
"I hate to cast any skepticism on what seems to be a great story of a brave spy coming in from the cold in the service of American freedom," says author Naomi Wolf at her Facebook page, but there's plenty about Snowden that doesn't add up. For one thing, "he is super-organized, for a whistleblower." A bigger tell is his lack of legal representation. Seriously, "where is Snowden's lawyer as the world's media meet with him?"

It may seem bizarre to suggest the NSA is purposefully outing its own secrets, Wolf says, but "it is actually in the Police State's interest to let everyone know that everything you write or say everywhere is being surveilled, and that awful things happen to people who challenge this."

"The questions may be reasonable or may turn out to be groundless," Wolf adds in an update, but we know that domestic police and spy agencies infiltrate protests and disrupt domestic political and news events. "Why should it be seen as bizarre to wonder, if there are some potential red flags — the key term is 'wonder' — if a former NSA spy turned apparent whistleblower might possibly still be — working for the same people he was working for before?"

6. Snowden is giving us a general wake-up call about cyber-privacy
Sometimes it takes a while to see the effects of current events, "and after all the debate about what [Snowden] did, history will have to decide if it's really a moment of infamy," says columnist and Democratic strategist Donna Brazile. But we are obviously in a period of immense societal change — "a Cyber Revolution," if you will — and apparently "Snowden is warning us that we need to pay better attention."

It makes me wish for the days when the biggest threat to my privacy was the giggling teenager listening in on the telephone party line. Perhaps in this age of plug-ins, Facebook and Twitter, our definition of privacy has changed. We're in an information free-for-all. Or free-fall. Still, when it comes to data mining, maybe there's a difference between business and government. According to Snowden, at least, the U.S. government should be acting differently....

I'm not discounting his idealism. He clearly is genuinely concerned about NSA's massive data-mining program. He described the U.S. spy program, meant to protect us against terrorists and enemies, as a "panopticon" — a composite of two Greek words that means "to see all." Before we try to "see all," maybe we should try to "see clearly".... Omniscient data gathering is part of the worldwide Cyber Revolution; countries — and corporations — with far less commitment to civil liberties than the United States are doing the same. [Daily Journal]