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.