Generals forced out after deadly Afghanistan base attack at Camp Bastion last year

(CBS News) Two U.S. Marine generals have been forced out of the military for failing to defend a major base in southern Afghanistan. Camp Bastion came under deadly attack by the Taliban last year. Investigators say the generals were not prepared to deal with outside threats.

The September 2012 attack on Camp Bastion left two Marines dead, and destroyed more than $100 million in military jets and other equipment. Maj. Gen. Mark Gurganus was the top Marine commander on the base. CBS News' Kelly Cobiella interviewed him a month later. Asked if he knew how they got through all of the defenses, he said, "I can tell you exactly how they got in. There's no great mystery to it. There were no suicide bombers, there were no tunnels. It's a tool about this big (gestures) and it cuts wire.

U.S. Marines recount deadly Camp Bastion attack

Cobiella said, "That's it. A wire cutter."

The general replied, "That's it. That's how they got in."

On Monday, Maj. Gen. Gurganus and the top Marine aviation officer at the time, Maj. Gen. Gregg Sturdevant, were asked to retire for not "exercising the level of judgment expected of General Officers" to protect Camp Bastion, according to Gen. James F. Amos, Marine Commandant.

Fifteen insurgents carried rocket-propelled grenade launchers, assault rifles and suicide vests and went after harrier jets and attack helicopters. The Taliban released a video days later, showing insurgents training for the assault. Military investigators say Maj. Gurganus was focused solely on threats from within, and didn't deploy enough troops to protect the perimeter. Gurganus said, "There are guard towers with guards in them, we have more sophisticated surveillance equipment, but it can't see everywhere all the time."

British forces were in charge of security at Camp Bastion. A four-month investigation found the tower closest to the attack was unmanned that night. The Marine commandant said both generals were "extraordinary officers" with distinguished careers, but said "Marines can never place complete reliance for their own safety in the hands of another force."

Lt. Col. Christopher Raible, a fighter pilot and commanding officer, died defending the base, along with aircraft technician Sgt. Bradley Atwell.

Watch Cobiella's full report above.