Many sexual assaults in the military go unreported, and programs to prevent or respond to those assaults aren't getting the institutional support they need, the U.S. Government Accountability Office said in a report.

The agency said the programs are "hindered" by commanders who don't support the programs or by military leaders who don't know how to implement the programs in areas where troops are deployed. Inconsistent training and a shortage of specialists in mental-health care are also blamed for program failures.

"Left unchecked, these challenges can discourage or prevent some service members from using programs when needed," the report said.

The agency's report, released late last month, was a response to congressional direction in 2004 for the Department of Defense to come up with a comprehensive policy to prevent and respond to sexual assaults that involve service members. The Coast Guard was also required to come up with a policy.

The GAO's list of 13 "interested" congressmen who requested copies of the report include presidential candidates John McCain and Barack Obama.

Despite the report's findings, La Rue Campbell, Hill Air Force Base's civilian coordinator for its sexual-assault program, said Hill has "very robust and proactive" programs aimed at dealing with sexual assault, with two response coordinators to carry out those programs.

Col. Linda Medlar, commander of Hill's 75th Air Base Wing, said Hill's leaders were "extremely active and supportive" in responding to sexual assaults.

"Sexual assault impacts mission capability and readiness," she said. "Without a ready force, the Air Force cannot defend the air, space and cyberspace from our enemy."

Medler said Hill has a "no tolerance" approach toward sexual assault involving military members, on or off duty. Efforts at Hill — which has more than 20,000 civilians and airmen working at the base — include using 25 volunteer advocates for sexual-assault victims. The volunteers train new airmen and future supervisors how to recognize what constitutes sexual assault and to understand the options for reporting an incident.

Hill officials declined to provide statistics on sexual assaults at the base.

The Utah National Guard also refused to provide numbers on assaults, saying it doesn't keep statistics on trends of reported incidents, according to Utah Guard Lt. Col. Kurt Davis, the sexual-assault response coordinator with Joint Force Headquarters for both the Air and Army Guard in Utah.

The Guard's program in Utah resembles Hill's, with a cache of trained victim advocates, support from commanders and help that is close at hand. The Utah Guard has 5,300 members in the Army Guard and 1,500 members in the Air Guard. About 580 soldiers and airmen are currently deployed to Iraq, Afghanistan and other places in the Middle East and Europe.

Guard members have access to help through the Department of Veterans Affairs, Davis said.

"As members of the National Guard, we use many of our community-based programs and medical facilities, due to limited military facilities," he said. "If our members are deployed, they have access to all of the active-duty military facilities and help, just like their active-duty counterparts."

But the GAO report found that a lack of help or support is silencing victims of sexual assault. The report included analysis of sexual-assault data, as well as surveys and interviews with over 3,900 service members to see how new or revamped policies are working.

Based on the most recent surveys conducted at 14 installations around the country and overseas, investigators found that half of 103 service members who said they were sexually assaulted did not report the incident.

"Factors that discourage service members from reporting a sexual assault include the belief that nothing would be done," the report stated. Fear of ostracism, harassment, ridicule and concern about peer gossip were also reasons for not reporting the assaults.

Throughout the 2007 fiscal year, the Defense Department received 2,688 reports of alleged sexual assault that involved servicemembers as victims or offenders.

The report accused the department and the Coast Guard of not having clear objectives, milestones, performance measures or criteria for measuring progress when it comes to oversight of dealing with sexual assaults.

Although Congress in 2004 had directed a Defense Department task force to look into matters relating to sexual assault, that task force as of July 2008 had not begun its review, the GAO report said.

Undersecretary of Defense for Personnel and Readiness David Chu wrote a letter last month to Brenda Farrell, the GAO's director of Defense Capabilities and Management, saying his department agrees with the report. Its recommendations include having Chu review and evaluate Defense Department policies on response and prevention. Chu said the task force would take steps that include visiting a number of installations to evaluate whether sexual-assault policies are working.