Garry Trudeau is the creator of the comic strip “Doonesbury.” Loree Sutton, a retired Army brigadier general, is a psychiatrist and founding director of the Defense Centers of Excellence for Psychological Health and Traumatic Brain Injury. She appears briefly in the film “The Invisible War.”

“The officer bragged to his fellow officer friends that he had ‘bagged’ me. I got called up to a major’s office, and he charged me with fraternization and adultery.”

— An active-duty Marine, speaking of her rape, in “The Invisible War”

If there is a defining theme in all of the testimony in “The Invisible War,” the searing documentary film released thisweek about military sexual assault, it’s betrayal. An estimated 19,000 rapes and sexual assaults took place in the military last year. Every one of them represents a monstrous crime made much worse by the sense of betrayal that accompanied it. That so few victims — just one in seven — report these crimes underscores the utter lack of trust that pervades military culture.

This should be deeply alarming to the armed services, which have professed a “zero-tolerance” policy for years — but have little to show for it. Trust is critical to any team endeavor, but in the military it can be the difference between life and death. The idea of “having someone’s back” is borrowed from the warrior’s real-life lexicon. Without trust, nothing works in the military. And because it is experience that forms trust, if a soldier’s experience tells her that she will not receive support and justice if she is attacked from within her ranks, she ceases to be an effective team member and suffers overwhelming personal consequences. You have lost that soldier forever. Multiply her by 19,000, and the impact on overall readiness is profound.

The military is about big, bold values, stitched into mottos, drilled into heads. Respect, trust, duty, honor, patriotism — these unambiguous values are evoked without irony. They allow down-range warriors the confidence to roll out of their cots and plunge into the horrific daily demands of their profession. They know that their brothers and sisters have their backs — and that they will take heroic measures to protect them.

Consider, then, what it does to the psyche of a soldier when he or she is stalked and attacked by that trusted teammate. The average rapist is a lifetime offender and adept at developing protective coloration. His peers often cannot believe he is capable of such crimes, so the victim is, at best, ignored — especially if the perpetrator is a friend of the superior to whom the victim must report. According to one Defense Department study, 33 percent of victims who don’t report say they don’t proceed for this reason alone. Twenty-five percent say they don’t report because the commander they must report to is the rapist. And when the rapist is a superior — the very person our service members have been trained to trust and obey — it’s easy to see why so many victims develop a level of post-traumatic stress disorder far exceeding the impact of war-zone combat.

For all these reasons, Defense Secretary Leon Panetta’s plan to transfer responsibility from unit commanders to an officer further up the chain of command is only a promising first step. If the Pentagon really means to fix the problem of military assault, it must begin by restoring trust in the system. The many victims who have looked in vain to majors and lieutenant commanders for justice can be forgiven for a little eye-rolling at the suggestion that they will receive it from colonels and captains in the future. There is deep cynicism about any solution that keeps the decision-making within the military installation or unit structure, where old-boy networks still rule and where careers are hardly advanced by reporting and documenting rape within the ranks.

In our view, the only credible solution is to create an independent special victims unit completely outside the unit chain of command, under civilian oversight. It should be led by a flag-rank officer who has no stake in the reputation of individual commands but a huge stake in doing the only thing that matters — driving down the rate of sexual assault in the military. Any such office would need to ensure leader accountability for the “gateway behaviors” — bullying, humiliation, scapegoating — that set the conditions for violent assault. Another Defense Department study found that the incidence of rape triples in units that tolerate sexual harassment.

This will not be easy, even for an independent authority. The military is both a closed system and a target-rich environment, and a career offender currently has little reason to believe he will be apprehended and punished. Several Navy studies administered anonymously reveal that as many as 15 percent of men have attempted rape or have raped someone before they enlisted — twice the percentage of their age-matched peers. Compounding this reality, men and women who enter the military are more likely to have been abused or sexually assaulted before they enlist, a traumatic experience that places them at greater risk for repeated assault. The military population is thus more likely to assault as well as to be assaulted. Isolated duty stations and its closed system for reporting, investigating and prosecuting crimes have made the military, this country’s most trusted government institution, a predator’s paradise.

To be clear, the vast majority of rape and sexual assault crimes are committed by a small minority of service members who relentlessly select, stalk and assault their prey. Most service members would never commit such a crime. But until basic trust can be restored to the culture, there is no reason to believe the Pentagon will ever end the sexual violence that has wreaked such havoc within the ranks.