WASHINGTON (ABC NEWS) -- Army Sgt. Bowe Bergdahl left his combat outpost in Afghanistan in 2009 and fell into enemy hands for five years, but the former Taliban prisoner wasn't the only trooper to sneak out of a U.S. base in recent years, military sources told ABC News on Sunday.
"At least a dozen guys just walked off their posts" in Afghanistan since 2009 for a variety of reasons, said an experienced soldier, one of four Afghan war veterans familiar with the incidents who spoke to ABC News. The other sources estimated the number could be more than a dozen.
The highly experienced combat veterans -- whose deployments cover the entire Afghan campaign -- said the significant incidents spanned a timeframe from when President Bush in late 2008 boosted conventional troop numbers in Afghanistan to well beyond President Obama's early 2010 surge that added 30,000 more troopers to the fight.
The soldiers discreetly slipped "outside the wire" to find drugs or were already intoxicated, left to "hang out" with local Afghan villagers or Afghan forces, or just simply snuck away without any idea where to go or what to do, the Army sources said.
"There was one kid who walked off his camp with an axe and some beef jerky with a plan to walk to Iran. The Afghan Local Police found him and brought him back," a second seasoned soldier with many deployments to Afghanistan confirmed.
The most infamous incident involved Staff Sgt. Robert Bales, a Stryker Brigade soldier who left a U.S. special operations camp in Kandahar province one night in March 2012 without authorization or apparently being noticed and entered a local village. Bales gunned down 16 Afghan civilians, half of whom were small children, and set their remains on fire. He was charged with murder by the Army, pleaded guilty and received a life prison term.
Military officials declined comment on Sunday. A spokesperson for the Office of Secretary of Defense Chuck Hagel referred an ABC News reporter to NATO's International Security Assistance Force in Kabul, which in turn said U.S. Central Command was the proper authority to comment on the issue. A spokesman for that combatant command based in Tampa, however, said it was a matter that should be addressed by the U.S. Army since it involved soldiers leaving their posts. An Army spokesperson advised a reporter to contact ISAF and CENTCOM.
There is no evidence that any of the soldiers who walked off post were charged with any form of desertion or intended to join the enemy. All were disciplined in various ways, the military sources said.
"This happens in wartime," said Gary Solis, a retired Marine Corps prosecutor who has taught law at West Point and Georgetown University.
Bergdahl's intentions once he left Combat Outpost Mest in Paktika province remain murky to officials five years later, though Army leaders have said they will hold him accountable as part of his reintegration process should any misconduct be proven.
In 2010, a Green Beret staff sergeant at Forward Operating Base Salerno in Khost took one of his teammates and a low-level "Category One" Afghan interpreter on an unauthorized joyride outside the base which ended in a deadly shootout with Afghan National Security Forces at a checkpoint, the four soldiers told ABC News, including sources who knew the Special Forces operator and a senior officer who is familiar with details of the case.
"While off base, they were mistakenly engaged by Afghan forces," the senior officer said. "The interpreter died and the SF soldier was wounded... I believe the SF soldier was administratively separated from the Army as a result of this."
One soldier who knew the joyriding Special Forces soldiers said they were suspected of being high on hashish, a highly concentrated form of marijuana, which is a cash crop in Afghanistan. But blood test results were misplaced.
"They took his beret and gave him the boot," the soldier said.
The senior officer said the investigation did not turn up evidence of drug use, but acknowledged drugs and alcohol are often prevalent at many outposts, including Special Forces camps. Bales admitted to using steroids, which he claimed altered his mood.
"Pills are huge over there because they're so cheaply made in Pakistan," said the first soldier, whose background and knowledge was verified by other soldiers.
"It was certainly not unheard of in Vietnam," added Solis, a Vietnam veteran, referring to both substance abuse as well as troops walking off their combat bases. "In Afghanistan, there were so many outposts 'away from the flagpole' out in the countryside."