A Pentagon investigation is under way into the posting of hundreds, and perhaps thousands, of nude photos of female Marines. Here, members of the service march in the Veterans Day Parade in New York City last November. Spencer Platt/Getty Images

Hundreds of Marines are reportedly under investigation by the Naval Criminal Investigative Service, after a trove of photographs were shared online that show female service members and veterans in the nude. The images were spread via a closed Facebook group with thousands of members.

When the photos were shared via Marines United — a Facebook group that’s intended only for male Marines and Marine veterans — they drew bawdy and obscene comments, according to two nonprofit news sites: the War Horse and the Center for Investigative Reporting.

According to War Horse founder Thomas James Brennan, many of the photos on the Marines United page included personal information about the female service members, from their name, rank and duty station to the names of their social media accounts.

The Facebook page also included links to a Google Drive with even more images — and an invitation to any members to contribute photos. The images were obtained in a variety of ways, Brennan reports, from sharing by former partners to stalking and, potentially, the hacking of service members’ personal accounts.

Almost immediately after the War Horse contacted the Marine Corps about the images in late January, the service asked Google and Facebook to delete accounts linked to the material, and an NCIS inquiry was begun, the site says.

“This behavior destroys morale, erodes trust and degrades the individual,” the Marine Corps says in a statement about what it calls “social media misconduct.” The service says those involved could face charges based on at two portions of the Uniform Code of Military Justice — one that involves consent and an expectation of privacy, and another that centers on distributing indecent material.

“A Marine who directly participates in, encourages, or condones such actions could also be subjected to criminal proceedings or adverse administrative actions,” the Marine Corps says.

There’s been a sharp backlash against those who publicly exposed the group, according to Marine Times:

“The news report was authored by Thomas Brennan, an Iraq and Afghanistan combat veteran and Purple Heart recipient who founded The War Horse in 2016. The nonprofit news site focuses on military and veterans affairs, and tales of combat heroism.

“After its publication, several members of the Facebook group lashed out at Brennan, making threats against him and his family.”