Three ballistic missile crew members from the Minot Air Force Base who fell asleep while holding classified launch code devices will be disciplined, the Air Force said Thursday.

"Actions have been initiated, including appropriate disciplinary measures or other sanctions," the Air Force said in a statement. "We demand adherence to the highest standards in all our activities involving nuclear weapons."

The Air Force would not say whether the discipline would include courts-martial or Article 15 reviews, which allow punishments without a court proceeding or public record.

"We can not release details until the process is complete," said Maj. Laurie A. Arellano, an Air Force spokeswoman.

The crew members, two lieutenants and a captain from the 91st Missile Wing, were in a missile alert facility about 70 miles from Minot when they fell asleep in a crew rest area on July 12, the Air Force said.

The military said a probe found the missile launch codes were outdated and remained secure at all times.

The incident involving the slumbering crew members was the first of two embarrassing incidents for the 91st Missile Wing last month.

On July 31, a vehicle carrying a rocket booster for an unarmed Minuteman III intercontinental ballistic missile overturned while being transported from the Minot Air Force Base to a launch facility in northwestern North Dakota, the Air Force said. Officials said no one was seriously injured and the public was not in danger.

Arellano said Thursday that crews were still working to retrieve the truck and booster rocket, which is 66 feet long and weighs 75,000 pounds, a week after the vehicle crashed on a gravel road near Makoti about 70 miles from the base.

Arellano said the recovery effort was expected to continue at least through the weekend.

The Minot Air Force Base has been under scrutiny since last August when a B-52 bomber from the base's 5th Bomb Wing was mistakenly armed with six nuclear-tipped cruise missiles and flown to Barksdale Air Force Base in Louisiana.