After high-profile accounts have been attacked — including AP's, NPR's and the BBC's — Twitter considers how to thwart hackers and protect users. iStockphoto.com hide caption

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This 12-story building houses a Chinese military unit allegedly behind dozens of cyberattacks on U.S. and other Western companies. It's in a modern, if bland, part of Shanghai. Peter Parks/AFP/Getty Images hide caption

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An analyst works at a federal cybersecurity center in Idaho in 2011. Experts say Internet-connected infrastructure is a possible target of cyberwarfare. Mark J. Terrill/AP hide caption

itoggle caption Mark J. Terrill/AP

Cyberattack headquarters? The 12-story building in a Shanghai suburb that American investigators say houses an operation responsible for hundreds of cyberattacks on companies around the world. Peter Parks /AFP/Getty Images hide caption

itoggle caption Peter Parks /AFP/Getty Images

DefCon Kids camp co-founder Chris Hoff, with Conner Gilliam (from left), Conner Fine and Ethan Lai, work on a machine that draws designs on ping-pong balls. The camp is held in Las Vegas. Steve Henn/NPR hide caption

itoggle caption Steve Henn/NPR