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Declaring "enough is enough," the top U.S. Marine on Tuesday told senators that he intends to fix the problem that led to current and former Corps members sharing nude photos of female Marines online and making lewd or threatening comments about them.

But angry and skeptical members of the Senate Armed Services Committee demanded more, saying the military hasn't done enough to combat sexual assault and harassment despite years of complaints and problems.

Gen. Robert Neller, the Marine Corps commandant, vowed to hold Marines accountable through whatever legal and other means possible. He acknowledged the scandal may hurt female recruiting and that changes have to be made in the Marine Corps culture, where some male Marines don't accept women in the ranks.

To some senators, his testimony rang hollow. He faced a particularly fierce barrage of questions and criticism from the women members of the panel.

Related: Nude Photo Posts of Female Marines Being Investigated by NCIS

"This committee has heard these kinds of statements before," said Sen. Jeanne Shaheen, a New Hampshire Democrat.

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"It's hard to believe something is really going to be done," she said "Why should we believe it's going to be different this time than it has in the past?"

Fellow Democratic Sen. Kirsten Gillibrand of New York said accusations of online exploitation of women by Marines came up in 2013, and victims have come forward.

Related: Who’s Policing Facebook’s Secret Groups?

"When you say to us it's got to be different, that rings hollow," Gillibrand said. "If we can't crack Facebook, how are we supposed to be able to confront Russian aggression and cyber-hacking throughout our military? It is a serious problem when we have members of our military denigrating female Marines who will give their life for this country in the way they have with no response from leadership."

Neller and the acting Navy secretary, Sean Stackley, said the Naval Criminal Investigative Service is looking into the matter. While some women victims have come forward, they said they need more to do so.

Stackley said an NCIS tip line has gotten more than 50 calls, and officials are finding and investigating more similar websites.

"This is a bell-ringer," said Stackley. "We're not going to go backwards."

He also noted the legal hurdles that make it more difficult to prosecute some online behavior that may be protected by certain privacy laws or as free speech. Questions remain, he and Neller said, about what can be done if someone voluntarily provides a nude photo or posts one online.

Lawmakers suggested possibly beefing up laws or regulations to specifically make what is called "revenge pornography" illegal under the Uniform Code of Military Justice.

Neller also said that while regulations can prohibit Marines from visiting certain places — such as strip clubs or other such locales — there are no similar restrictions on websites.

On Tuesday, chief of Naval operations Admiral John Richardson cautioned in a message to 3,000 Naval leaders that "we have a problem and we need to solve it."

"Really solve it, not put a band-aid on it, not whitewash over it, not look the other way," Richardson said.