JACKSONVILLE, N.C. — A decade after the Pentagon began confronting rape in the ranks, the U.S. military frequently fails to protect or provide justice to the children of service members when they are sexually assaulted by other children on base, an Associated Press investigation has found.

Reports of assaults and rapes among kids on military bases often die on the desks of prosecutors, even when an attacker confesses. Other cases don’t make it that far — criminal investigators shelve them, despite requirements they be pursued.

The Defense Department doesn’t know the scope of the problem on its bases. AP documented nearly 600 sex assault cases since 2007 through dozens of interviews and by piecing together records and data from the four main military branches and schools the Pentagon runs in the U.S. and abroad.

Assaults that would be addressed by juvenile rehabilitation and punishment programs if they happened in the civilian world instead get lost in dead zones for justice on bases.

“The military is designed to kill people and break things,” said former Army criminal investigator Russell Strand, a pioneering expert on military sexual assault. “The primary mission, it’s not to deal with kids sexually assaulting kids.”

Strand estimated that during his 32 years as an investigator or trainer, colleagues passed on opening several hundred cases. He was among a dozen current or former prosecutors and military investigators who described how policies within the Pentagon and U.S. Justice Department, which has jurisdiction over many bases, thwarted efforts to help both victims and offenders.

The tens of thousands of kids who live on bases are not covered by military law. Because the Justice Department isn’t equipped or inclined to handle cases involving juveniles, it rarely takes them on.

An AP analysis of about 100 investigative files showed that federal prosecutors pursued roughly one in seven juvenile sex offense cases at Navy and Marine Corps bases. In one unprosecuted case from Japan, witnesses confirmed that a 17-year-old boy pulled a 17-year-old girl from a parked car to his residence, where she said he raped her. A medical exam of the girl found his semen.

Sex assault cases can be difficult to investigate and prosecute, more so when they involve children. Offenders may threaten further harm, victims may not want to relive the trauma.

When victims on bases do press for justice, they can feel abandoned. At a U.S. Army base in Germany, Leandra Mulla told investigators her teenage ex-boyfriend dragged her to a secluded area and thrust his hand down her pants while forcibly trying to kiss her. Four years later, Mulla still wonders what came of her report.

“The military is a great field to be in,” she said. “But they just like to cover up what goes on because they have an expectation and they try to uphold an image.”

Offenders, meanwhile, typically receive neither therapy nor punishment, and some are shuffled to other installations or into the civilian world.

Heather Ryan is still haunted by a case at North Carolina’s Marine Corps Base Camp Lejeune she worked when she was a Naval Criminal Investigative Service agent.

A 10-year-old boy had confessed to sexually assaulting his two half-sisters. Ryan couldn’t get him help from the military’s vast support structure. Ultimately, his family transferred.

“I think of him a lot and wonder how he’s doing,” Ryan said, “and if he has hurt anybody else.”

The Defense Department told AP it “takes seriously any incident impacting the well-being of our service members and their families” and promised to take “appropriate actions” to help juveniles involved in sex assaults.

AP found the otherwise data-driven Defense Department does not analyze reports it receives of sexual violence among kids on base. When the Pentagon said it could not pinpoint the number of assault reports, AP used U.S. Freedom of Information Act requests to obtain investigative reports and data from the agencies that police the Army, Air Force, Navy and Marines, as well as the Pentagon’s school system.

Records the military initially released omitted 200 cases AP ultimately identified. Undisclosed cases came from large bases that records listed as having no or few sexual assaults in Alaska, Colorado, Missouri, Texas, Germany and Italy.

Records at the Department of Defense Education Activity, the Pentagon school system which educates 71,000 students, were in such disarray that dozens of forms recording sexual assaults were misclassified as “child pornography” reports.

Pentagon school officials said safety was their highest priority and administrators must report all incidents. Months after AP began questioning the handling of student sex assaults, school officials said they were developing new rules and guidance for reporting and responding to such violence.

A spokesman said the Justice Department does not comment on how its attorneys select cases. Federal prosecutors are supposed to hand juvenile cases to their local counterparts whenever possible. AP found few bases where that regularly happened.

When prosecutors don’t get involved, a base commander may ban an offender pending therapy, or transfer the family. They are not, however, required to take action.

Failure to act misses a crucial opportunity: Research suggests that only 5 percent of juveniles who are arrested for a sex offense will get caught reoffending.

Pritchard reported from Los Angeles. David Rising in Berlin, Germany, contributed reporting. Also contributing were Rhonda Shafner and Jennifer Farrar in New York, and Yuri Kageyama in Tokyo.