The most significant factor, according to advocates, is the perception by victims in the military that they lack the recourses available in the civilian world to bring assailants to justice.
"The military says they have zero tolerance, but in fact that's not true," said Dr. Katherine Scheirman, a retired Air Force colonel with more than 20 years of service in the U.S. and abroad. "Having a sexual assault case in your unit is considered something bad, so commanders have had an incredible incentive not to destroy their own careers by prosecuting someone."
Insisting it takes the problem seriously, the military has put in place numerous policies and programs to reduce the assaults, notably since the 1991 Tailhook scandal in which Navy pilots were accused of sexually abusing female officers at a Las Vegas convention.
Still the problem persists, as indicated in a recent Pentagon report estimating that 26,000 service members were sexually assaulted last year, compared with 19,000 in 2011. Victims reported 3,374 incidents in 2012; there were convictions in 238 of those cases.
"That means there are thousands of felons walking around -- free and dangerous -- in the military today," said Sen. Barbara Boxer, D-Calif.
Boxer is co-sponsor of a bill that would remove top commanders from the process of deciding whether sexual misconduct cases go to trial. Instead, that decision would rest with officers who are trial counsels with prosecutorial experience.
To advocates for assault victims, that would be a crucial step forward, given Defense Department findings that many victims are of lower rank than their assailants and most fear retaliation if they report the incident.
The missing element is accountability, according to Nancy Parrish of Protect Our Defenders, one of the groups urging changes in the military justice system.
"When military leaders are held accountable for countenancing bad behavior, then you'll begin to see a shift in the culture," she said. "They've proved they can do this with racial integration. Anyone who countenanced racist behavior would be fired."
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, has conveyed the same message, calling sexual assault "a crime that demands accountability and consequences" and describing it as "a serious problem that we must solve."
Outrage over the Pentagon's failure to stem the problem has grown following an embarrassing string of arrests and incidents of sexual misconduct. On Friday, in the latest disclosure, the Pentagon confirmed that the U.S. Naval Academy is investigating allegations that three football team members sexually assaulted a female midshipman at an off-campus house last year.
Some longtime advocates for assault victims say they've grown weary of promises to do better.
"They say they are dismayed, saddened, committed to making change, but all their rhetoric really boils down to is, 'How do we not get caught?'" said Paula Coughlin, who as a Navy lieutenant in 1991 was instrumental in bringing the Tailhook scandal to light.
"There's an environment in the military that says you can get away with it -- you don't go to jail if you attack women," said Coughlin.
In the civilian world, positions of power often are exploited by sexual abusers, as evidenced by the many cases involving clergymen, coaches and teachers.
Scheirman, now a physician in Edmond, Okla., said issues of power and control are particularly pronounced in the military.
"Commanders have the power to destroy your career, to make your life a living hell," she said. "Though 99.9 percent of them don't, you can't take that chance. If it was a commander who assaulted you, you'd be delusional to think that if you reported it, any justice would be done."
While precise comparisons are difficult, the Defense Department's recent report suggests that women in the military and the civilian world face roughly the same risk of sexual assault. One crucial difference is that most civilian victims have options, such as going to the police or filing a civil suit, in the aftermath of harassment or assault that aren't available to service members.
"In civilian world, all of these recourses act as a deterrent," said Anu Bhagwati, a former Marine captain who advocates on behalf of assault victims as executive director of the Service Women's Action Network.
In the military, Bhagwati said, "there's no freedom of movement, no right to quit your job, You're forced to coexist with your perpetrator."
Cynthia Smith, a Defense Department spokeswoman, says the military does offer options to assault victims, who can report incidents to a sexual assault response coordinator, a victim advocate, a health care provider or a chaplain.
The contrasts between the military and corporate America are stark to Marene Nyberg Allison, who was in the first class of women at the U.S. Military Academy, graduating in 1980. After six years in the Army, she became an FBI agent, served on a Defense Department advisory committee on women in the military, and is now a senior executive with Johnson & Johnson.
"If I go on a business trip and someone tried to sexually assault me, I could sue them, I could sue the company, I could sue just about everybody," she said. "In the military, you're not allowed to do that."
"At a corporation, no one is asking, 'Does a woman really belong here?" she said. "You see that in the military -- this whole idea of 'Do women belong here at all?'"
Steps are being taken.
Two weeks ago, Defense Secretary Chuck Hagel ordered the military to recertify all 25,000 people involved in programs to prevent and respond to sexual assault. On Thursday the Defense Department launched a service called The Safe HelpRoom, enabling assault victims to participate in group chat sessions providing support and referrals.
Bhagwati says the biggest strides toward achieving lasting change would be to double the representation of women in the military from the current level of 15 percent and end the exclusion of women from certain units and missions. In particular, she said, more women are needed as officers, so they have the collective confidence to push for change.
"It's hard for women to go against the grain," she said. "It's not a culture that teaches moral courage, as opposed to battlefield courage."
It's also a culture that has been conducive to sexism and the degradation of women, Bhagwati contends.
"At bases overseas, there's commercial exploitation of women thriving around them, women being trafficked," she said. "You can't expect to treat women as one of your own when, in same breath, you as a young soldier are being encouraged to exploit women on the outside of that base."
"We don't condone that kind of behavior," insisted Cynthia Smith. "We work in an environment where we need to treat everyone with respect."
Jessica Kenyon, who served with the Army in South Korea, recalled a pervasive tendency to scapegoat women.
"If there are any problems in the unit -- sex, drinking and driving, anything that could possibly be tagged to women being in the unit -- it's seen as their fault," she said.
Kenyon said her Army career derailed after she was raped and impregnated by a fellow soldier in 2006. Now 32, she runs online support services for military victims of sexual assault.
"I treat my cases like they are incest survivors," she said. "You're willing to take a bullet for the guy you just met and to have that trust willfully violated makes the sense of betrayal that much higher."
One notable aspect of the Pentagon's recent sexual-assault estimates was the level of male-on-male assaults. Men were the victims in nearly 14,000 of the estimated 26,000 assaults, although women, comprising a small fraction of active-duty personnel, had a higher rate of being assaulted.
"Men need to be encouraged to come forward, so if you ask for help, it's seen a sign of strength, not of weakness," said Paul Rieckhoff, a former Army officer who heads Iraq and Afghanistan Veterans of America.
Allyson Robinson of Servicemembers Legal Defense Network, one of the groups which successfully campaigned to let gays serve openly in the military, said repeal of "don't ask, don't tell" has given more male soldiers the confidence to report same-sex assaults.
"Under 'don't ask,' service members who were victims of assault by their own sex could have been accused of being gay if they reported it, and thus lose their careers," she said.
She disputed suggestions from some conservatives that repeal of "don't ask, don't tell" is responsible for an increase in male-on-male assaults.
"Sexual assault is never about sex or sexual orientation," she said. "It's a crime of violence that's about power and domination."
Cynthia Smith said commanders will be the key to any improvements.
"No one should be at risk -- male or female," she said. "Commanders are expected to provide the necessary resources or training so that both men and women know where to turn should they have questions or need support."
Dempsey, among others, suggests that the sexual assault problem has been aggravated by the strains of wars in Iraq and Afghanistan. Professor David Segal, director of the University of Maryland's Center for Research on Military Organization, said such strains are a key factor in the surge of suicides, spousal abuse and other problems in addition to sexual assault.
"The military has been phenomenally stretched over the last decade -- it's been asked to do too much for too long with too few resources," he said. "The veneer of civilization is very thin, and the wars have worn it down or cracked it."
Follow David Crary on Twitter at http://www.twitter.com/craryap
Protect Our Defenders: http://www.protectourdefenders.com
Service Women's Action Network: http://servicewomen.org
The Safe HelpRoom: https://safehelpline.org/about-safe-helproom
Defense Department: http://tinyurl.com/bo95o68
Copyright 2013 The Associated Press.