A decade after a series of rape charges sparked a major effort to protect female cadets at the Air Force Academy, the Pentagon today launched an investigation into a spate of new cases in which female cadets said they were disciplined, ostracized or forced to leave the academy after reporting sexual assaults by fellow students.

Female cadets who reported being raped by male upperclassmen within the past two years have said they were warned by fellow cadets that they could face official discipline for underage drinking and "fraternization" -- that is, personal relations with a military superior -- if they brought formal charges against the men involved. Some cadets said they were told that assault in a social setting, such as a date or a party, is so difficult to prove that charges against the men involved would be futile.

The new Pentagon probe follows news stories on Denver's KMGH-TV and in the Denver weekly newspaper Westword. Both outlets interviewed female cadets involved in a series of alleged assaults from early 2000 to last fall.

Sen. John W. Warner (R-Va.), chairman of the Senate Armed Services Committee, and Sen. Wayne Allard (R-Colo.) called on the Defense Department and the academy to investigate the specific cases reported and the general circumstances surrounding sexual assault at the academy.

The academy has declined to comment on the specific cases cited in the Denver news reports. As a general matter, the academy superintendent, Lt. Gen. John Dallager, said in a statement, "We don't tolerate and condone sexual harassment, much less sexual assault. We are not going to sweep it under the rug." The academy has promised complete cooperation with a five-member working group sent from the Pentagon.

That group, headed by Kelly Cravens, deputy assistant secretary of the Air Force for force management, began work at the academy's Colorado Springs campus today. An Air Force statement said, "While the Air Force Academy has had a program in place since 1993, recent cadet complaints suggested a review is now appropriate."

"They did make changes in '93, but they haven't dealt with the basic problem in the corps of cadets," said Dorothy Mackey, a former Air Force captain who now counsels military rape victims through STAMP, or Survivors Take Action Against Abuse by Military Personnel, an organization she runs from her home in Ohio.

"There is tremendous pressure on these cadets, men and women, not to break silence," Mackey said. "If you're raped, the whole academy -- the corps of cadets and the administration -- wants you to keep it to yourself. They turn against you if you report a fellow cadet."

Many universities have a problem with sexual assaults between students, Mackey noted, but the situation may be exacerbated at a military academy.

"That upperclassman is not only your date, he's your superior officer," she noted. "You're trained all day to do what your superior tells you to do."

One of the "recent cadet complaints" aired on KMGH last week came from a woman who said she had become romantically involved with an upperclassman during her freshman year. The older cadet regularly provided alcohol to her and other freshmen, the woman told KMGH reporter John Ferrugia. One night when both were drinking, she said, her date led her to a dark spot and raped her.

The young woman said other female cadets strongly advised her not to report the incident, warning that she would suffer retaliation from upperclassmen and could face charges for underage drinking. After she kept the secret for months, the cadet said, the emotional baggage grew so heavy that she dropped out of the academy in 2001. She could now face a bill for the year and a half of education the Air Force provided her.

The new surge of complaints, and the investigative panel looking into them, parallels what happened 10 years ago, when Air Force Academy officials received a series of complaints from female cadets of sexual harassment or assault.

That triggered various changes in rules and procedures on the campus.

The most visible was the creation of Cadets Advocating Sexual Integrity and Education, or CASIE, an organization of cadet volunteers who counsel victims of sexual assault or harassment and advise them of their options.

CASIE rules state that a victim "will generally not be disciplined for self-identified violations of cadet instructions which may have occurred in connection with the assault."

But the women making the recent complaints have said they were threatened with disciplinary action for their own misdeeds at the time of an assault.

"That's how they keep the victims quiet," said Mackey, of STAMP. "The idea is, if you want to ruin the career of the guy who attacked you, we'll see to it that your career is ended, too."