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U.S. military leaders sent out guidance to personnel about online conduct in the wake of a recent nude-photo sharing scandal on social media.

The Navy, Air Force and Army have sent out messages, following the Marine Corps' lead after news broke that Marines had been sharing nude and compromising photos of female colleagues on a 30,000-member Facebook page called Marines United.

The Naval Criminal Investigative Service launched an investigation earlier this month into the site, which members used to post revealing and sometimes nude photos of the Marines; identifying information such as names and duty stations; and degrading and misogynistic comments.

Critics and lawmakers have pointed to an ingrained sexism and misogyny in the Corps, which is now integrating women into combat roles.

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Commandant Gen. Robert Neller sent a "White Letter" on March 10 to all senior leaders in the service, ordering them to support self-identified victims of Facebook harassment and illicit photo sharing, and to educate troops on what is expected of them in their conduct online.

To prevent future social media fallout, Neller said Marines must be educated, not only on the service's expectations for their online behavior, but also on the dangers and vulnerabilities inherent in online activity.

The Corps will soon publish an update to its 2010 guidance governing Marines' social media activity to further this goal, he said.

The Navy's Chief of Naval Operations Adm. John Richardson wrote a March 14 blog post addressing all commanders fleetwide about the problem.

"The discovery of online sites that degrade the female members of our team has shined a light on the fact that this problem persists. But we get reminders of it every day, when we disrespect women by crude jokes, wisecracks, sexual harassment, and in its worst manifestation, sexual assault -- a serious violent crime. Despite a steady effort to get after this, we're not making progress," Richardson wrote.

"This demeaning activity offends so many of us because fundamentally, this is not how we treat true teammates."

Richardson said he expects all commanding officers to challenge command leaders at the small-team level, with "division officers and chiefs talking to their divisions, branches talking to branches."

"Talk about what respect for our teammates looks like at work, at home, and online. Make it clear that individuals who can't live up to our professional standards in competence and character are not welcome in our Navy.

"Make it clear that our standards call us to a higher commitment than the law -- we are better than that. And finally, I expect you to make it crystal clear that to remain the world's most powerful Navy, we must be 100% focused on staying ahead of our competition, which starts with leadership and teamwork, built on trust and respect."

Air Force Chief of Staff Gen. David Goldfein addressed all airmen about the recent scandal in a March 10 statement.

"People are the foundation of our Air Force. Our mutual support for each other is based on dignity, respect and trust ... a Wingman culture. As Wingmen, we must continuously demonstrate courage and strength of character to do and say the right things, at the right times, to protect each other ... there is no other acceptable option," Goldfein wrote.

"When Airmen fail to live up to our core values -- Integrity First, Service Before Self and Excellence in All We Do -- the reputation of all who serve and have served is tarnished. These values apply to behavior on social media. Any conduct or participation in activities, whether online or offline, that does not adhere to these core values is NOT acceptable.

"From our newest airman basic to the chief of staff, we are all accountable for meeting ethical and performance standards in our actions. We should live our core values every day ... on and off duty."

Goldfein and Chief Master Sgt. of the Air Force Kaleth Wright also released a similar message on video March 17.

The Army sent out its social media guidance in a letter, dated March 17 and signed by acting Secretary of the Army Robert Speer, Army Chief of Staff Gen. Mark Milley, and Sergeant Major of the Army Daniel Dailey.

The letter calls on soldiers and Army civilians to treat each other with dignity and respect.

"Recent misconduct on social media has deeply affected our military community," the letter states.

"We are all figures of public trust and our conduct must be exemplary. Standing shoulder-to-shoulder with fellow soldiers from reception stations through basic training, AIT, and combat deployments builds trust that is forever weakened or erased when a fellow soldier is victimized by disparaging and degrading comments made in person or posted on social media.

"The assumption of anonymity on social media is false. Active participation and passive tolerance of online misconduct are equally destructive to the foundational trust essential to our ability to decisively fight and win the Nation's wars."

The letter directs leaders from the squad level up to "talk about and demonstrate what respect looks like at work, at home, and online."

"We expect soldiers and civilians to adhere to AR 600-20, Army Command Policy, and the Army's Online Conduct Policy, which together state that harassment, bullying, hazing, stalking, discrimination, retaliation, or any other type of misconduct are contrary to Army Values," according to the letter.

-- Matthew Cox can be reached at matthew.cox@military.com.