Sexual assault occurs in many settings and the perpetrators come from every swath of U.S. society. Yet, as recent incidents and reports make clear, it’s a particularly intractable problem in the military.

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.”

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 U.S. Sen. Barbara Boxer.

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.”

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.

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,” 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.”

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?’ ”

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.”