WASHINGTON -- From Congress to the White House, pressure is mounting to hold military commanders accountable for the rising number of sexual assaults in the armed services.

The extent of the assaults came to light when the Pentagon released a report earlier this month estimating that as many as 26,000 military members may have been sexually assaulted last year and that thousands of victims are unwilling to come forward despite new oversight and assistance programs. That figure is an increase over the 19,000 estimated assaults in 2011.

Several recent arrests have added to the military's embarrassment. A soldier at the U.S. Military Academy at West Point was charged with secretly photographing women, including in a bathroom. The Air Force officer who led the service's Sexual Assault Prevention and Response unit was arrested on charges of groping a woman. And the manager of the Army's sexual assault response program at Fort Campbell, Kentucky, was relieved of his post after his arrest in a domestic dispute with his ex-wife.

"This needs to end," Republican Sen. Lindsey Graham, a member of the Armed Services Committee, said Sunday. "When a victim comes forward, they should have an advocate to walk them through the military justice system, and commanders who allow this to continue to allow this to flourish quite frankly should be fired."

Democratic Sen. Dick Durbin said the military's future includes both men and women in leadership, and cultural changes are needed "when it comes to the command structure" to make sexual assault and harassment "unacceptable, intolerable; and those who engage in it should pay a price."

Retired Marine Gen. John Allen, who retired in February after 19 months commanding allied forces in Afghanistan in order to attend to his wife's health issues, encouraged commanders to address the issue and tell subordinates exactly what was expected.

"Commanders can't be ambiguous about this. We can't not talk about that," Allen said Sunday. "Commanders (have) got to stand in front of their units and tell the people what they expect. Because silence isn't good enough. This is an opportunity to lead, and we should be seizing it."

The comments from Durbin, Graham and Allen capped a week of attempts to address the Pentagon's findings. President Barack Obama and Defence Secretary Chuck Hagel raised the issue separately in graduation speeches at the U.S. Naval Academy at Annapolis and the U.S. Military Academy at West Point.

"Those who commit sexual assault are not only committing a crime; they threaten the trust and discipline that makes our military strong," Obama said Friday. "That's why we have to be determined to stop these crimes, because they've got no place in the greatest military on Earth."

Hagel called on the graduating West Point cadets Saturday to use their leadership to address the epidemic.

"This scourge must be stamped out. We are all accountable and responsible for ensuring that this happens. We cannot fail the Army or America. We cannot fail each other, and we cannot fail the men and women that we lead."

Members of a House panel on Wednesday approved legislation that would strip commanding officers of their longstanding authority to unilaterally change or dismiss court-martial convictions in rape and assault cases. The bill would also require that service members found guilty of sexual offences be dismissed or dishonourably discharged. The legislation will be folded into a broader defence policy bill that the full House of Representatives will consider in the coming weeks.

Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, has acknowledged the severity of the problem. He said recently that military leaders are losing the confidence of the women who serve that they can come up with solutions.

But Dempsey said in a May 20 letter to the chairman of the Senate Armed Services Committee that any legislative remedies must maintain the commander's role in the military justice process. Cutting them out or limiting them too severely would undercut their authority to enforce discipline and execute their duties, he wrote.

"Good order and discipline is essential to military efficiency and effectiveness," Dempsey said in the letter to Sen. Carl Levin, chairman of the Senate Armed Services Committee. "Removing commanders from the military justice process sends the message to everyone in the military that there is a lack of faith in the officer corps and the serving commanders. Conveyance of a message that commanders cannot be trusted will only serve to undermine good order and discipline."

Dempsey and the chiefs of the military services are scheduled to testify June 4 before the Senate Armed Services Committee on legislation to prevent sexual assaults.

Sharon Disher graduated from the Naval Academy in 1980 in the first class that included women. She said Friday she's disappointed the military is still grappling with sexual assault issues but applauded the president for raising the subject.

"The more we talk about it, the more we're going to do something about it, and that's the thing we never did," she said. "I guess we've just got to keep the conversation going until we fix the problem."

Durbin and Graham spoke on "Fox News Sunday." Allen appeared on ABC's "This Week."