The two-star general in charge of all Air Force nuclear missiles was fired Friday following a probe into alleged personal misbehavior -- just days after another key official overseeing U.S. nuclear power was relieved of duty. 

The Air Force announced Friday that Maj. Gen. Michael Carey was removed from command of the 20th Air Force, which is responsible for three wings of intercontinental ballistic missiles -- a total of 450 missiles at three bases across the country. 

The circumstances of Carey's firing were unclear. Two officials told the Associated Press it had to do with alcohol use. 

A senior U.S. Defense official said he was fired over "conduct." Officials said that it did not have to do with gambling, or the loss of a nuclear weapon, or sexual misconduct. 

Lt. Gen. James Kowalski, commander of Air Force Global Strike Command, made the decision based on details from an inspector general probe into Carey's behavior on a "temporary duty assignment," according to the Air Force. 

"20th AF continues to execute its mission of around-the-clock nuclear deterrence in a safe, secure and effective manner," Kowalski said in a statement. "It's unfortunate that I've had to relieve an officer who's had an otherwise distinctive career spanning 35 years of commendable service." 

Earlier in the week, the Navy announced that the deputy commander of U.S. nuclear forces, Vice Adm. Tim Giardina, was relieved of duty amid a military investigation of allegations that he used counterfeit chips at an Iowa casino. 

The move was already exceedingly rare, and followed by Friday's decision at the Air Force. 

Kowalski has selected the vice commander of Air Force Global Strike Command, Maj. Gen. Jack Weinstein, to temporarily replace Carey as head of 20th Air Force. 

Fox News' Justin Fishel and The Associated Press contributed to this report.