WASHINGTON -- Battered by a nude photo-sharing scandal, the Marine Corps has issued a longer and more detailed social media policy that lays out the professional and legal ramifications for service members culpable of online misconduct.

Among the coming changes: a requirement that all Marines sign a statement acknowledging they have read and understand the new guidelines.

The adjustments are designed to give leaders more leeway in prosecuting or punishing offenders. Former and current female Marines have reported their photographs and those of women in other services being posted on social media pages without their consent.

Get Breaking News Delivered to Your Inbox

Investigators are also looking into threatening and obscene comments Marines wrote accompanying the images.

The new policy makes it clear how existing rules and the Uniform Code of Military Justice can be used to prosecute offensive, indecent or disrespectful online activities. But it creates no new laws, underscoring the legal quagmire posed by the internet and the constraints on military leaders posed by privacy laws and the First Amendment right of free speech.

Released in recent days by Gen. Robert Neller, the Marine commandant, the Corps’ new guidance is one result of the ongoing criminal investigation.

“Marines should think twice before engaging in questionable online activities, and must avoid actions online that threaten the morale, operational readiness and security, or public standing of their units, or that compromise our core values,” the policy states, addressing any content or comments that are deemed defamatory, threatening, harassing or discriminating on the basis of race, color, sex, gender, age, religion, national origin, sexual orientation or other criteria.

It makes clear that bad behavior can be punished under the military code.

The Marine Corps isn’t the only service making changes. The Army is sending out a new message to its force, signed by senior leaders including Gen. Mark Milley, the Army chief of staff, and warning soldiers that online misconduct is unacceptable and passive tolerance of bad behavior by others is also wrong. The Army has routinely updated its social media policy to emphasize treating soldiers with dignity and respect, including in February before the Marine scandal surfaced.

The services are urging any victims of improper photo-sharing to come forward. The Naval Criminal Investigative Service said it is getting more tips every day, but investigators acknowledge the legal hurdles in finding and prosecuting offenders.

Twenty women have reported that they’re victims. The probe has expanded in the last two weeks, as services beyond the Marines examine if their members are involved. So far, they say no victims from the other services have come forward. No men have said they were victimized.

One problem for investigations is that photos were shared by Marines and others on a private Facebook page that was members-only and men-only. And they were mainly housed on a Google Drive linked to the page. The Facebook page has been taken down and that Google drive link is also gone, although officials say the photos likely migrated to other sites.

Because the page is gone, investigators must rely on screenshots showing the screen names of military members, as well as reports from victims who heard about or saw the images. Tracking offenders is difficult because many may not use real names.

Another challenge: The bulk of the photos are selfies. Many were likely provided willingly by the person in the picture to someone else, or possibly posted on Instagram or another such site. The question then becomes whether sharing an explicit photo that was provided willingly is a crime.

A number of states have laws prohibiting so-called revenge pornography, and the military is looking at making a similar addition to its code, a change several senators are suggesting. But such a law may require prosecutors to prove the posting’s intent was to harm the individual and that it had an impact. Both can be difficult to prove.

Officials also have to tread carefully to avoid restricting free speech. As an example, attempting to prohibit anyone from looking at or posting a nude photo on the internet would be difficult to do and nearly impossible to enforce.

The military, however, has greater ability to punish service members beyond strictly legal violations. Officers can be charged with conduct unbecoming an officer, and service members can be punished for harming the good order and discipline of their unit, or their military service. These broader categories give commanders greater flexibility in ordering administrative punishment or even forcing service members to leave the military.

The nude-photo sharing scandal surfaced earlier this month. The Defense Department has been investigating online outlets through which Marines shared nude photographs, and the probe widened to include all military branches, CBS News national security correspondent David Martin reported.

The website titled Anon-IB first gained notoriety for publishing nude photos of celebrities like Jennifer Lawrence. It also contains a message board for military personnel where men from all branches of the military exchange comments and nude photos of female service members, sometimes identifying them by name and/or duty station.

This military-wide message board came to light just days after the exposure of a Facebook group called Marines United, which included nearly 30,000 active duty and retired Marines, some of whom shared nude photos of female Marines along with raunchy and sexually violent comments.

Erin Kirk-Cuomo, who left the Corps in 2010, told CBS News female Marines were complaining about sites where photos were shared even then.

“This is an ongoing issue. It’s not something new,” she said. “This is something that has been pervasive and has been going on for over a decade.”

Kirk-Cuomo believes it is part of a culture that begins with boot camp when women recruits are segregated from the men.

“This behavior is ingrained in Marine Corps culture simply because they as male Marines are told from the very beginning of training that females are inferior,” she said.

Top brass in the Marines have denounced misbehavior by Marines in vigorous terms.

“There is no place for this type of demeaning or degrading behavior in our Corps,” said Sergeant Major Ronald L. Green, 18th Sergeant Major of the Marine Corps in a statement to CBS News earlier this month.