Marine Corps unit commanders need to take immediate steps to ensure their troops are in compliance with the Corps' social media standards, according to a new Marine administrative message released late Wednesday night.

The Corps is encouraging Marines troops to be vigilant about social media use and to search their own names online to see what personal data information might already be public after a "kill list" featuring photos and addresses of 100 U.S. troops service members was posted by a self-proclaimed division of the Islamic State group. The new MARADMIN emphasizes the responsibility of Marine commanders to ensure their Marines know the rules and are minimizing the danger to themselves through their social media interactions.

Published online in late March by tThe self-described Islamic State Hacking Division published the list, now removed, in late March. It included the names of 41 Marines and sailors. The According to a Marine administrative message published lateWednesday, Naval Criminal Investigative Service has notified all 41 troops and is working with law enforcement and U.S. intelligence agencies to evaluate and address the threat, according to the MARADMIN.

The message emphasized that the "kill list" did not require an elaborate hack or data infiltration.

"The data ISIL retrieved on service members was not the result of hacking into Department of Defense networks, it was obtained from public internet sites," the message reads. "ISIL then used this data as a form of internet harassment called doxxing, which is the practice of revealing personal, private, or identifying information about people online for various reasons such as extortion, coercion, harassment, public shaming and vigilante justice."

In light of the threat, commanders are directed to immediately" to ensure compliance with existing policies and make sure official unit websites, including social media pages and biographies, follow guidelines for operational security. They are also asked to direct their personnel to examine their own online presence and eliminate information that might put them at risk.

Commanders should encourage Marines to continue to use personal social media as they normally would, the message said, but with additional caution to maintain operational security and avoid publishing personal information. While they can make unofficial posts regarding the Marine Corps and Marine-related topics related to their expertise, officials said they should avoid discussing troop movements, force size, weapons system details and other classified or controlled information.

Troops should also be mindful not to reveal too much about themselves, the message said. Examples of personal identifiable information that should not be released include a Marine's personal home address, birthday and birth place, according to the message.

To determine what personal information might already be available on publicly accessible websites, out in the world, the message encourages unit commanders to direct their troops to do online searches for their own names and personal information. If anything compromising turns up, Marines "should attempt to remove or otherwise render inaccessible potentially sensitive information," the message said. If they have trouble doing so, they should involve their chain of command to assist.

While the information compiled for the the "kill list" included names and data taken from news stories and the Defense Department's own media releases, the service is Marines are not currently considering a change to existing public affairs and information release policies, said Lt. Col. John Caldwell, a spokesman for Headquarters Marine Corps.

"We're merely directing to ensure current policies are being followed," he said.

Commanders are also encouraged to have their Marines read the Corps' social media handbook to familiarize themselves with all other existing policies. The message emphasized that the Corps is not trying to restrict use of social media within current guidelines.

"Social media is an invaluable tool for information sharing," officials wrote in the message. "But it must be used in a responsible manner if we are to protect our Marines, sailors, civilians and family members and safeguard this mission."

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