The Marine Corps is banning access to social networking sites from its computer systems. No more Twitter, Facebook or MySpace for the few, the proud.

An order issued Monday says social networking sites (SNS) are off limits for the next year. "These internet sites in general are a proven haven for malicious actors and content and are particularly high risk due to information exposure, user generated content and targeting by adversaries." The order says the sites, by their very nature, expose "unnecessary information to adversaries." Marines can request a waiver to use the sites if necessary.

Blog: Twitter Takes a Hit

Wired Magazine broke the story this afternoon, speaking to the Pentagon's "social media czar", Price Floyd, who says a balance must be found between security needs and the real world uses of social networking. "What we can't do is let security concerns trump doing business," Floyd tells Wired. "We have to do business… We need to be everywhere men and women in uniform are and the public is. If that's MySpace and YouTube, that's where we need to be, too."

LiveLeak has been a popular website for many servicemen and women, a place where they can upload videos of their time in combat. That will now be off-limits to Marines (they probably weren't supposed to upload those videos anyhow), and the ban on social networking could expand to other parts of the military as the Defense Department weighs the pros and cons. Ironically, the Chairman of the Joint Chiefs Staff, Admiral Mike Mullen, has 4,000 followers on Twitter. His latest "tweet"?: "Recently finished reading 'The Bookseller of Kabul' by Asne Seierstad. Powerful insights into the lives of Afghan women and girls." No security leak there.

The news comes the same day the Boston Herald writes about an Arizona couple which recently "tweeted" while on vacation, only to discover upon their return that they'd been burglarized. Malicious actors are everywhere...

UPDATE: Adm. Mullen has updated his Twitter account with this message:

"Obviously we need to find right balance between security and transparency. We are working on that. But am I still going to tweet? You bet." 

On CNBC.com a special series on Social Networking: Social Climbers  

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