The number of nuclear missile launch officers under investigation for allegations of cheating has nearly doubled, a U.S. military official said Tuesday.
On Jan. 15, the Air Force announced that 34 nuclear officers were under investigation for either cheating on tests or knowing about the cheating ring and not reporting it.
As the investigation continued, investigators identified more individuals who were involved in or knew about the cheating, nearly doubling the number from the original 34 — although officials wouldn't give an exact number.
"The number of officers under investigation has increased," the official said, but declined to give the exact number now under investigation. The official also could not say how many officers have been suspended from duty, saying only, "It is safe to assume that if they are under investigation, they are not pulling duty."
The official, who spoke to NBC News on condition of anonymity, stressed that there has been no change in the overall nuclear mission and no degradation of the U.S. nuclear capability.
The original officers in the probe, all assigned to the 341st Missile Wing at Malmstrom Air Force Base in Montana, are accused of apparently texting answers to each other on a monthly proficiency exam, or knew that the cheating was going on and didn't report it, according to officials.
The monthly exam tested the officers' knowledge of the missile launch systems. It was administered in August and September 2013.
Air Force Chief of Staff General Mark Welsh said earlier this month the officers shared the exam "electronically.” Text messages were involved, he said. He would not expand on the exact circumstances of the alleged cheating, citing an ongoing investigation.
At the time, Welsh said that there was no indication the cheating scandal extended beyond the 34 officers.
There are about 190 missiliers at Malmstrom, one of three U.S. Air Force bases responsible for the ICBM program.
Air Force Secretary Deborah Lee James, the service's top civilian official, has said that the alleged cheating at Malmstrom was discovered during a previously announced probe of drug possession by 11 officers at several bases. Initially, that probe only included 10 officers.
The 341st Missile Wing provides security for 150 nuclear-armed Minuteman 3 intercontinental ballistic missiles, one third of the entire ICBM force, according to the Associated Press.
NBC News' Elizabeth Chuck contributed to this report.