BEIJING, May 15 (Xinhuanet) -- The U.S. Department of Defense said it will block worldwide access to 13 websites including MySpace and YouTube Today from the unclassified defense Department Internet(NIPRNet), according to media reports Tuesday.

    U.S. Army Gen. B.B. Bell issued a memo Friday stating that use of social networking and recreational Web sites strains network capabilities and presents operational risks.

    The memo states that soldiers cannot access the sites through military networks, the only lines of communication open to many on active duty in foreign countries. They can still access the sites from their home computers.

    "The Department of Defense has a growing concern regarding our unclassified DoD Internet, known as the NIPRNet," wrote Bell. "The commander of DoD's Joint Task Force, Global Network Operations (JTF-GNO) has noted a significant increase in use of DoD network resources tied up by individuals visiting certain recreational Internet sites."

    This regulation is intended primarily to prevent military internet connections from being clogged with uploads or downloads of data-rich files such as video clips, said Defence Department spokesman Commander Jeffrey Gordon.

    The restriction bans almost 3 million employees, including those working overseas, from accessing the sites using the department's computers.

    They're also urged to be cautious about information they transmit from their home computer to work.

    Although the new policy is in line with previous edicts barring military personnel from any form of communication that could jeopardize safety or mission security, some observers are crying foul because of the role MySpace and YouTube play in allowing overseas troops to stay in touch with their stateside family and friends.

    (Agencies)