The Pentagon released an alarming report on sexual assault in the military yesterday, prompting Senator Patty Murray to introduce a bill aimed at helping victims and curbing what she called a “disgusting epidemic.”

The figures confirmed what a lot of people suspected: Sexual assault is rampant in the military and getting worse. Last year, the number of reported assaults rose 6 percent to 3,374, and the number of unreported assaults is likely much higher. Extrapolating from a survey of service members not required to reveal their names, the Pentagon reckons that roughly 26,000 soldiers have experienced unwanted sexual contract, from rape to groping.

But here’s something that most people probably wouldn’t expect: An estimated 13,900 of these assaulted soldiers are men.

Don’t look to the military brass to figure out this phenomenon. In Congressional testimony yesterday, Gen. Mark Welsh blamed society at large. “Some of it is the hookup mentality of junior high even and high school students now, which my children can tell you about from watching their friends and being frustrated by it.”

But widespread sexual assault, particularly when targeted at men, doesn’t sound like high school. It sounds like prison.

And indeed there would seem to be some similarities between prison and the military. Ticking off reasons why sexual assault on men might be happening in the military, Arthur Satterfield, a counselor at the Seattle Vet Center specializing in sexual trauma, says “access and availability.” There simply are far more men in the military than women .

“Stress level plays into it,” Satterfield adds. “Also,” he says, “the military is an institution that is very hierarchical.” That’s important, he suggests, because “this type of behavior is not about sex but about power and control.” He says that, usually, it’s a superior officer–in his experience, most often a man– who is asserting control over a lower ranking service member.

Alcohol is often a significant factor as well in sexual assaults in the military, whether on men or women, says Glenna Tinney, a retired captain who once managed a sexual assault program for the Navy and now works for the Battered Women’s Justice Project. That adds up, given the heavy use of so-called self-medication by war-scarred soldiers.

At the end of the day, though, we simply don’t know much about the sexual abuse of men in the military, according to Elspeth Cameron Ritchie, a Washington D.C. area psychiatrist who previously served in the Army’s Office of the Surgeon General. That’s because so few men report it. Even in today’s military, which no longer abides by the homophobic code of “Don’t Ask, Don’t Tell,” Ritchie says soldiers are afraid of being labeled a “faggot.”