Thirty-four United States Air Force officers in charge of nuclear launch duty have been suspended for allegedly cheating in proficiency tests, media reports said Thursday.

The cheating, which is reported to have occurred at the Malmstrom Air Force Base in Montana came to light during a drug probe involving 11 officers at several Air Force bases, the Associated Press reported, adding that the cheating incident is the latest in a series of scandals that have undermined the country’s nuclear missile force.

Air Force Secretary Deborah Lee James, who took charge about four weeks ago as the service's top civilian official, told a press conference that she was "profoundly disappointed" with the revelations and called the cheating “absolutely unacceptable behavior," AP reported.

"Some officers did it," James said of the cheating, according to BBC. "Others apparently knew about it, and it appears that they did nothing, or at least not enough, to stop it or to report it."

According to Gen. Mark Welsh, the Air Force chief of staff, one launch officer at the Malmstrom base was found to have sent one or more text messages to 16 other launch officers with answers to a test, AP reported. Meanwhile, 17 other launch officers "self-admitted to at least being aware of material that had been shared. We don't yet know how or if each of those officers used that material, but we do know that none of them reported the incident to their leadership."

Sen. Mark Udall, D-Colo., who is chairman of the Senate Strategic Forces Subcommittee, asked for immediate action to be taken against the offenders, AP reported, and said: "There simply is no room in our Air Force, and certainly in our nuclear enterprise, for this type of misconduct."

In recent months, the Air Force nuclear force has come under fire for safety violations, training breakdowns and burnout among the force’s personnel, AP reported, adding that, in October, the commander of the nuclear missile force was fired for drunken behavior during a nuclear exercise in Russia.

Navy Rear Adm. John Kirby, a spokesman for Defense Secretary Chuck Hagel, said Hagel had demanded a running update of the investigation, AP reported, adding that about 600 members of the missile launch officer force would be re-tested this week.

“I want you to know that this was a failure of some of our airmen. It was not a failure of the nuclear mission," James reportedly told the news conference.