In fiscal year 2013, which ended Sep 30 last year, a total of 5,061 sexual abuse complaints were received, compared to 3,374 cases the previous year.
"Sexual assault is a clear threat to the lives and the well-being of the women and men who serve our country in uniform. It destroys the bonds of trust and confidence that lie at the heart of our armed forces," US Defence Secretary Chuck Hagel said at a press briefing Thursday about the report.
He pointed out that he had issued 22 directives on preventing and responding to sexual assaults in the past year and announced an additional six directives, including an order for a department-wide review of institutional alcohol policies.
"There is no indication that this increase in reporting constitutes an increase in crime," Maj. Gen. Jeffrey Snow, director of the Pentagon's Sexual Assault Prevention and Response Office, said at the briefing.
"We assess that this unprecedented increase is consistent with a growing confidence in the response systems," he said.
The armed forces are treating cases of sexual abuse via the military justice system and, according to the new figures, 73 percent of the people accused of abuses were ultimately disciplined because there was sufficient proof against them, compared to 66 percent the year before.
For years, the military has kept sexual abuse problems in the shadows, and they were not reported because of the culture of respect for rank, out of fear of public ridicule or because of attempts by senior officers to avoid scandals.
Congress and the administration of President Barack Obama have taken steps in recent years to improve prevention and strengthen enforcement of the law when it comes to sexual abuse cases.