Everyone from troops in the field to the highest brass and civilian leaders will be allowed to Twitter, blog and use Facebook and other social networking sites on the military’s non—classified computer network, the Pentagon announced.

The new policy follows a seven-month review in which the Defence Department weighed the threats and benefits of allowing the wide use of emerging Internet capabilities. It essentially seeks to manage the risks while acknowledging the Internet is proving a powerful tool for a myriad of tasks including recruiting, public relations, collaboration with a wide range of people and for communications between troops and their families.

To guard security, it allows commanders to cut off access - on a temporary basis only - if that’s required to safeguard a mission or reserve bandwidth for official use. The new directive also makes practices uniform across the entire department, in which different commands previously blocked certain things while others didn’t. Visiting sites for pornography, gambling or hate-crime activities is still prohibited on military computers.

“We need to take advantage of these capabilities that are out there - this Web 2.0 phenomena,” David M. Wennergren, deputy assistant secretary of defence for information technology, said on Friday. “The idea is be responsible and use these tools to help get the job done.”

The new directive means that YouTube, MySpace and more than a dozen sites blocked by the Pentagon in May 2007 will be unblocked, he said. The Pentagon said at the time that the use of video sites in particular was straining its network and using too much of its bandwidth. But Wennergren said the move failed to stem the use of bandwidth because people just went to alternate sites.