YouTube.com, MySpace.com and other commercial social-networking applications

proved to be too popular at the Defense Department for their own good.

Saying these "entertainment sites" were sucking up network resources needed for more critical operations, the Pentagon is blocking access to 13 such sites beginning May 14.

Gen. B. B. Bell, commander of U.S. forces in Korea, announced the change in a memo released May 11.

But the memo also makes clear, without using his name, that Lt. Gen. Charles Croom, who serves as both the head of the Defense Information Systems Agency and commander of Joint Task Force-Global Network Operations, is behind the move.

“The Commander of [JTF-GNO] has noted a significant increase in use of DOD network resources tied up by individuals visiting certain recreational Internet sites,” the memo reads. “This recreational traffic impacts our official DOD network and bandwidth availability, while posing a significant operational security challenge.”

The blocked sites are YouTube.com, 1.fm, Pandora.com, photobucket.com, MySpace.com, live365.com, hi5.com, metacafe.com, mtv.com, ifilm.com, blackplanet.com, stupidvideos.com and filecabi.com.

The memo takes pains to point out that the access restrictions only apply to DOD systems and networks, not home computers.

This is the second time in less than two weeks that, in response to operational-security concerns, the military has implemented a policy affecting individuals’ ability to use aspects of the Internet.

On May 3, the Army issued a policy that appeared to shut down soldiers’ use of the Internet to send personal e-mails or contribute to blogs by requiring a supervisor’s approval before sending or posting anything, and — as written — it appeared to put similar limits on Army families.

The uproar was fast and fierce, and the Army issued a clarification May 5 stating that it did not include family members and was aimed at encouraging soldiers to receive guidance and awareness training from a security officer before posting to a blog.

Patience Wait is a staff writer for Government Computer News, an 1105 Government Information Group publication.