Sexual assaults in the U.S. military are a growing epidemic across the services and thousands of victims are still unwilling to come forward despite a slew of new oversight and assistance programs, according to Pentagon documents.

Troubling new numbers estimate that up to 26,000 military members may have been sexually assaulted last year, according to survey results released against a backdrops of scandals including an ongoing investigation into more than 30 Air Force instructors for assaults on trainees at a Texas base

The report comes just days after the Air Force's head of sexual assault prevention was arrested last weekend on charges of groping a woman in a suburban Virginia parking lot. And it follows a heated debate over whether commanders should be stripped of the authority to overturn military jury verdicts, such as one officer did in a recent sexual assault conviction.

President Barack Obama delivered a sharp rebuke Tuesday, saying he has no tolerance for the problem, and he said he talked to Defense Secretary Chuck Hagel about it. He said that any military member found guilty of sexual assault should be held accountable, prosecuted and fired.

"I don't want just more speeches or awareness programs or training, or ultimately folks look the other way," he said. "We're going to have to not just step up our game, we have to exponentially step up our game to go after this hard."

The Associated Press obtained documents and memos related to a new Pentagon report slated for release Tuesday. The documents show that the number of sexual assaults actually reported by members of the military rose 6 percent to 3,374 in 2012. But a survey of personnel who were not required to reveal their identities showed the number of service members actually assaulted could be as many as 26,000, but they never reported the incidents, officials said Tuesday.

That number is an increase over the 19,000 estimated assaults in 2011.

The statistics highlight the dismal results that military leaders have achieved in their drive to change the culture within the ranks, even as the services redoubled efforts to launch new programs to assist the victims, encourage reporting and increase commanders' vigilance.

Hagel ordered a series of steps and reviews to increase officers' accountability for what happens under their commands, and to inspect workstations for objectionable materials, according to memos and documents obtained by the AP.

Hagel ordered military leaders to develop a method to assess commanders and hold them accountable on their ability to create a climate "of dignity and respect." He has given commanders until July 1 to visually inspect workspaces to make sure they are free of degrading materials, and military leaders have until Nov. 1 to recommend ways to assess officers and hold them accountable for their command climates.

"Sexual assault is a crime that is incompatible with military service and has no place in this department," Hagel said in a new response plan the department will release Tuesday. "It is an affront to the American values we defend, and it is a stain on our honor. (The Department of Defense) needs to be a national leader in combating sexual assault and we will establish an environment of dignity and respect, where sexual assault is not tolerated, condoned, or ignored."

While the latest cases involve Air Force members, the problem extends across all the military services.

In Congress, lawmakers demanded the Pentagon take more aggressive steps to address the growing problem and they announced renewed efforts to pass legislation to battle the problem.

"When our best and our brightest put on a uniform and join the United States Armed Forces, they do so with the understanding that they will sacrifice much in the name of defending our country and its people. However, it's unconscionable to think that entertaining unwanted sexual contact from within the ranks is now part of that equation," said Sen. Patty Murray, a Democrat. "Not only are we subjecting our men and women to this disgusting epidemic, but we're also failing to provide the victims with any meaningful support system once they have fallen victim to these attacks."

This week's sexual battery arrest of Air Force Lt. Col. Jeffrey Krusinski, who headed the Air Force Sexual Assault Prevention and Response unit, provided a rallying point for lawmakers, who held it up Tuesday as an example of the Pentagon's failure to make progress despite the increased effort.

Sen. Carl Levin, a Democrat, told Air Force officials at a Senate Armed Services Committee hearing on Tuesday that "while under our legal system everyone is innocent until proven guilty, this arrest speaks volumes about the status and effectiveness of (the Defense) department's efforts to address the plague of sexual assaults in the military."

Members of Congress are putting together legislation to essentially strip military officers of the authority to overturn convictions for serious offenses such as sexual assault. The measure stem from congressional outrage over an Air Force officer's decision to reverse a jury verdict in a sexual assault case.

___

Associated Press writer Richard Lardner contributed to this report.