The pictures of the women with their names, rank and duty stations were posted on a private Facebook group of 30,000 active and retired male members of the Marine Corps.
The explicit pictures of the women on "Marines United" were either taken without their knowledge or ripped from their social media accounts, eliciting obscene comments and misogynistic behaviour, a report published by The War Horse said.
Marines United contained a link to a Google Drive folder, where they were being stores. The photos included screenshots of the women's social media accounts, and images of sexual acts. The pictures may have been taken consensually, but had been either leaked or hacked.
The folder was removed after a Marine Corps veteran, Thomas Brennan, alerted authorities. The social media accounts run by those who shared the photos were shut down.
The Naval Criminal Investigative Service is now investigating.
What are people saying?
Social media users have expressed their anger at the news, but some have threatened Brennan with torture.
With a population of 7% of the Marine Corps, female Marines do not have the numbers to defend themselves against a culture of misogyny.— Maximilian Uriarte (@TLCplMax) March 6, 2017
This makes me so angry. Over 30,000 followers on that page. These women serve our country. They deserve better! https://t.co/Ik4QAXIaKt— Brenda Tracy (@brendatracy24) March 7, 2017
Brennan has received death threats for reporting the group.
Have there been other reports of sexual assault in the military?
The Pentagon's annual report, released in May 2016, showed that the the US military received about 6,000 reports of sexual assault in 2015.
But the figures could be much higher as many assaults are not reported.
Sexual assault in the military is so prevalent that statistics show a woman is more likely to be raped by a fellow soldier than killed in combat.
But even when cases are reported, sexual assault victims are stigmatised and some have been discharged after filing complaints.