The military received more than 6,000 reports of sexual assaults last year, but only a small fraction, about 250, led to a court-martial and conviction for a sexual assault-related crime, according to a new Pentagon report.

Released Thursday, the Pentagon’s annual report on military sexual assaults that was released Thursday showsed that about 4 percent of sexual assault complaints led to a conviction. 

Many sexual assault reports result in no punishment for an array of legal reasons that can include a lack of jurisdiction, lack of hard evidence, a commander's decision not to prosecute or because the alleged perpetrator separates from the military.

Defense officials say the low conviction rate is a concern.

Army Maj. Gen. Camille Nichols, the director of the Defense Department's Sexual Assault Prevention and Response Office, acknowledged that the services have not historically provided enough staff and resources to promptly examine all reports of sexual assault reports, a task that typically falls to the military's criminal investigation agencies.

"We needed more assets. … We needed more resources to investigate all the reports," she said.

But that is starting to change. Nichols said the military has reduced the lag time between an incoming report and an military-led investigation into its the underlying facts. Those investigations often require lawyers, laboratory testing, and staff to take witness statements and gather potential evidence.

"We are absolutely getting better resources, better trained personal.  We are on the right path," she said.

In total, the military officials received 6,083 reports of sexual assaults during fiscal year 2015, which ended Sept. 30. That's roughly similar to the number reported in fiscal 2014 the year before, according to the report. 

In the same year, there were 254 courts-martial that led to a conviction for a sexual-assault related crime, the report says said.

It’s widely believed that sexual assaults in the military are vastly under-reported. Data based on anonymous surveys of service members suggest that more than 20,000 troops may be sexually assaulted each year.

Pentagon officials say the low conviction in part reflects the nature of the criminal justice system and the rights of the accused.

"Yeah, it doesn't make us feel very comfortable that we can't, when an allegation is made, that we can't take every single allegation to court. But that is our justice system," said Nate Galbreath, a senior executive adviser for the Pentagon's sexual assault prevention and response program.

"We have a high standard — beyond a reasonable doubt — so there are always going to be many, many more reports about what happens every year, and allegations made, than what can be prosecuted in court," Galbreath said Thursday in a meeting with reporters at the Pentagon.

It's hard to compare the military's sexual assault data with the civilian sector because the Defense Department's military's record keeping is unique, and it's impossible to track all civilian reports lodged with police, employers, healthcare workers, and so forth etc.

Galbreath noted a long list of reasons why a complaint might not lead to a conviction.

Of those 6,083 initial complaints filed last year, about 1,500 of them were "restricted," reports, meaning the victim was a service member who reported the assault but refused to participate in any criminal investigation and only sought healthcare and victims' support services.

In 2015, military criminal investigators reviewed 4,584 "unrestricted" reports from victims who were willing to participate in a potential prosecution. But in many of those cases, are not prosecutable because the attackers’ identity was is unknown, the attacker may have separated from the military or the attacker might be a civilian who is not subject to the military court system.

After completing investigations, there were 2,783 cases that were sent to military commanders to consider some action. Here's the breakdown:

  • In 770 cases, a the commander determined there was not enough evidence to pursue the case any further.
  • CIn the 2,013 cases in which commanders determined there was sufficient evidence to pursue disciplinary action, the commanders substantiated some misconduct that was not unrelated to sexual assault in 576 cases.
  • Commanders substantiated some sort of misconduct related to sexual assault in 1,437 cases, but in 511 of those cases, the matter was resolved without a court-martial — with either a non-judicial punishment, an administrative discharge or other administrative action.
  • CIn 926 cases, commanders launched court-martial proceedings against the alleged perpetrator in 926 cases. Among those, 159 cases were closed because the alleged perpetrator resigned from the military, and 111 were closed because the case was dismissed in pretrial proceedings before reaching a court martial.
  • Of the 543 cases that ultimately went to court-martial, 130 resulted in not-guilty verdicts.
  • Of the 413 troops who were convicted at a court-martial, 161 of those cases resulted in convictions on charges that were not unrelated to sexual assault.
  • In 254 cases, a service member as convicted of a sexual assault-related offense.

At the end of 2015, courts-martial charges remained pending against 113 service members, according to the report.