Updated

A new Pentagon study shows that the number of sexual assaults reported by members of the military rose from 3,192 to 3,374 in 2012, while the department estimates that as many as 26,000 service members were assaulted, based on anonymous surveys, officials said Tuesday.

The troubling trends underscore service members' continued reluctance to come forward and formally report attacks. And the numbers highlight the dismal results that military leaders have achieved in their efforts to change the culture within the ranks. The numbers are included in the latest annual report on sexual abuse in the military, which comes just days after the arrest on sexual battery charges of an Air Force officer who headed the Air Force Sexual Assault Prevention and Response unit.

Sen. Carl Levin, D-Mich., 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."

Gen. Mark Welsh, the Air Force's chief of staff, told the committee that he and Air Force Secretary Michael Donley were "appalled" by Lt. Col. Jeffrey Krusinki's arrest. Although the case is being adjudicated by the Arlington County police, Welsh said the Air Force has requested jurisdiction.

The estimate of 26,000 sexual assaults is up from the estimated 19,000 in 2011, officials said.

Defense Secretary Chuck Hagel is ordering 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 obtained by The Associated Press.

Hagel is ordering military leaders to develop a method to assess commanders and hold them accountable on their ability to create a climate "of dignity and respect."

"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. DoD 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."