WASHINGTON (CNN) -- Six nuclear warheads on cruise missiles were mistakenly carried on a flight from North Dakota to Louisiana last week, prompting a major investigation, military officials have confirmed.
A B-52 is seen on the ground at Barksdale Air Force Base, Louisiana, in this file photo.
The plane took the cruise missiles from Minot Air Force Base to Barksdale Air Force Base for decommissioning Thursday, the Air Force said.
"This is a major gaffe, and it's going to cause some heads to roll down the line," said Don Shepperd, a retired Air Force major general and military analyst for CNN.
Shepperd said the United States had agreed in a Cold War-era treaty not to fly nuclear weapons. "It appears that what happened was this treaty agreement was violated," he said.
The warheads should have been removed from the missiles before they were attached to the B-52 bomber, according to military officials. Watch the report on the military's investigation »
The crew was unaware that the plane was carrying nuclear weapons, the officials said, speaking on condition of anonymity because of the extraordinary sensitivity and security surrounding the case.
The mistake was discovered after the plane's flight to Louisiana.
Minot Air Force Base is in north central North Dakota, and Barksdale Air Force Base is in northwest Louisiana near the Texas border.
Pentagon press secretary Geoff Morrell made clear that concerns about the "error" had escalated to the highest levels.
"Secretary [of Defense Robert] Gates was quickly informed of this incident ... and he has been receiving daily briefings from Gen. Buzz Moseley, the Air Force chief of staff, on actions that the Air Force is taking and the progress of their investigation," Morrell told reporters Wednesday.
"I can also tell you that it's important enough that President Bush was notified of it."
Democratic Rep. Ike Skelton, head of the House Armed Services Committee, called the revelation "deeply disturbing." He said Wednesday that the committee will press the military to "strengthen controls" after the incident.
Military officials told CNN that the incident was a major breach of security rules surrounding nuclear weapons. One official said that he could not recall anything similar happening.
The Air Force announced that all flights of fighters and bombers in the United States will be halted on September 14 to allow for a review of procedures.
Once the mistake was discovered, the Air Force immediately began an inventory of all of its nuclear weapons, a military official said.
Maj. Gen. Douglas Raaberg, director of Air and Space Operations at the Air Combat Command in Langley, Virginia, has been ordered to investigate how the nuclear-tipped missiles were flown across the country without anyone knowing, officials said.
The squad commander responsible for the munitions has been relieved of duty, and several others have been "decertified" from handling nuclear weapons, officials said.
A military official told CNN there was no nuclear risk to public safety because the weapons were not armed. Officials believe that if the plane had crashed or the missiles somehow had fallen off the wings, the warheads would have remained inert and there would have been no nuclear detonation, though conventional explosive material in the warhead could have detonated.
Military officials also say the missiles could not have been launched because of multiple security procedures required to be enacted before any launch would have been authorized.
Shepperd agreed with military officials that the situation could not have caused a nuclear detonation.
But he added, "Any time you have nuclear material on board, if the airplane crashes, nuclear material can be spread in the immediate area of the crash, so you get radioactivity in the immediate area of the crash."
"This is serious business, but it was not dangerous business," Shepperd said.
The story was first reported by the Military Times, a group of privately published newspaper. E-mail to a friend