When senators summoned Pentagon leaders to answer for a rash of sexual assaults in the military in 2013, the assembled brass were undivided in their resistance to plans that would strip commanders of their power over prosecuting those crimes, warning the changes would undermine discipline in the ranks.

Eight years later, opposition from top military officials — even as they pledge “zero tolerance” for a problem that has defied decades of attempted reforms — remains unchanged.

What has changed is the politics surrounding the issue, with new signals from the White House, an increased focus on the military’s lack of high-level diversity and shifting societal views on sexual assault in the wake of the #MeToo movement.

It’s unclear whether proposals that would give specialized military prosecutors, rather than unit commanders, the power to decide which alleged sexual assaults are subject to military trial will muster enough votes to pass in Congress. Among the measures being considered is one first introduced in 2013 by Sen. Kirsten Gillibrand (D-N.Y.) that the senator and co-sponsors hope to reintroduce this month.

Support for more systemic change appears to be growing as lawmakers express impatience with the military’s inability to curb an epidemic of sexual harassment and assault. And as momentum builds for change, Pentagon leaders are quietly facing a reckoning between traditional military norms and intensified pressure over the scourge of sexual assault.

“Every general or commander that has come in front of this body for the past 10 years has told us, ‘We’ve got this, ma’am, we’ve got this,’ ” Gillibrand said at a hearing in March. “Well, the truth is they don’t have it.”

Pentagon statistics show that reports of sexual assault in the military are on the rise, most often affecting female service members ages 17 to 24. Events such as the murder of Army Spec. Vanessa Guillen, who had confided to her family about sexual harassment before her death but did not report it to her superiors, have drawn attention to troops’ mistrust in the military justice process.

Scrutiny of sexual assault is growing at a time when the Pentagon, spurred partly by race-related unrest in 2020, launches new steps to address the underrepresentation of minorities and women in the upper ranks. Studies show that female service members are more likely to leave the military earlier than men, often citing the toll of sexual harassment and assault.

Like others before it, the Biden administration has promised aggressive action on sex crimes in the ranks. Shortly after taking office, Defense Secretary Lloyd Austin, the retired general President Biden named as the country’s first African American Pentagon chief, announced a three-month review by an independent commission.

Speaking to reporters last month, chair Lynn Rosenthal said the commission would make recommendations for “major shifts” in the handling of sexual assault and would study the proposal to take certain prosecution decisions out of the chain of command. “What’s different today, quite frankly, is this is not a closed door,” she said.

Advocates of the change proposed by Gillibrand describe it as a “light touch” that would leave most unit commanders’ powers intact. Already, previous changes have limited commanders’ ability to adjudicate subordinates, elevating the power to refer sex crimes to courts-martial to the level of Army colonels or Navy captains and restricting commanders’ ability to lessen punishment or overturn convictions.

Under the current system, those select commanders, with input from lawyers working under them, can decide whether cases involving their subordinates go to court-martial, result in lesser punishment or are dismissed.

But because commanders are not lawyers and often are inexperienced in handling sexual assault, advocates say, they are not adequately equipped to decide which cases should be tried. Moreover, because commanders may know the accused or may fear retaliation from their chain of command, troops may decide against reporting assaults.

The proposed legislation, in contrast, would give specialized military prosecutors outside the chain of command authority to refer felony-type crimes to courts-martial, including grave sex crimes and murders. Commanders would retain authority over lesser infractions and military-specific crimes like desertion or disobedience.

Don Christensen, a retired Air Force prosecutor who has advocated for the shift, said the change would apply to fewer than 150 officers now empowered to make prosecutorial referrals, a tiny share of commanders across the military.

But critics of the measure say it would undermine the central tenet of commanders’ responsibility for their subordinates and weaken those officers’ investment in deterring sexual assault because their career trajectories would no longer be tied to it. It would also disrupt a uniformed justice system that has a better record of sex-crime convictions than civilian courts. The real solution, they contend, is more prevention and accountability.

Multiple military-backed studies have reached the same conclusion. “It is neither feasible nor advisable to remove commanders as the central figure of the military justice system,” a 2020 study mandated by Congress found.

As in 2013, all of the military’s current service leaders, including Chief of Naval Operations Adm. Michael Gilday, Army Chief of Staff Gen. James McConville, Air Force Chief of Staff Gen. C.Q. Brown and Marine Corps Commandant Gen. David Berger, have voiced opposition to the Gillibrand proposal.

In 2019, Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, wrote that he “strongly supports” the present system. “The commander is responsible for everything the unit does and fails to do,” he said.

But current and former officials say military leaders may now feel constrained in forcefully articulating their opposition, in part because Biden, at a campaign event in 2020, had indicated support for the change and because previous eradication efforts haven’t worked.

“There’s a recognition the trend is going the wrong way and it’s not getting better,” said one former senior defense official who spoke on the condition of anonymity to discuss the issue candidly.

“If you look at it from that perspective, it’s hard to defend the department position,” the official said. “And whoever does that will come under intense scrutiny because the performance hasn’t been there.”

Through a spokesman, Milley, who was appointed by President Donald Trump, declined to comment on the proposal but called sexual assault “a form of fratricide” that must be stopped. “It is corrosive to the very essence of what it means to be in the military,” he said.

For Austin, the debate represents an intersection between the values he espoused during his 40-year military career and his new role as a political appointee. While he declined to state his position on the proposed change when asked by Gillibrand during his confirmation hearing, Austin has suggested he will accept the commission’s recommendations.

He may be especially likely to do so as he seeks to establish his credentials as a civilian leader following criticism of Biden’s decision to nominate a recently retired general, the second in four years, to head the Defense Department.

Pentagon spokesman John Kirby said Austin would keep an open mind. “He doesn’t want to take anything off the table as we try to tackle this again,” he said.

While Gillibrand’s proposal has secured support from Republican lawmakers including Sen. Charles E. Grassley (Iowa) and Sen. Ted Cruz (Tex.), Pentagon opposition has contributed to its failure to gain traction in past years. A proposal to make similar changes in the House, put forward last year by Rep. Jackie Speier (D-Calif.), likewise did not advance.

“The reason this has been stopped year after year is that the generals and the admirals have come in and said, ‘Don’t do this,’ ” Christensen said. “If the commander in chief supports it, that shuts them up.”

This year, Pentagon officials are eyeing several senators, including Jack Reed (D-R.I.), chairman of Senate Armed Services Committee, and Joni Ernst (R-Iowa), who they believe could embrace the proposal, and catalyze support from others, if Austin embraces it.

While Reed has voted against the plan in the past, spokesman Chip Unruh said he would review the commission recommendations. “The simple fact is, there is no easy fix or silver bullet here,” Unruh said.

In an interview, Gillibrand said she believed conditions in Congress — and society — were more favorable than they were in 2013 because of the #MeToo movement and because the incidence of military sexual assault has not improved. But, she said, she has detected no change from Pentagon leaders. She pointed to the military leadership’s history of resistance to racial and gender integration and more permissive policies for gay, lesbian and transgender troops.

“I think it’s part of the culture of the military to keep the status quo,” she said. “If you are top brass, it means you’ve succeeded in the current system. And so particularly the group of commanders are looking in and saying, ‘We did fine. This wasn’t a problem.’ ”