June 25, 2014  -- On March 11, 2012, Army infantry 1st Lt. Thomas Roberts typed up and signed a moral declaration that would not only end the Special Forces career of Maj. Jim Gant, but also would expose an open secret of U.S. special operations: the use of powerful pain medications, sleeping pills and alcohol to cope with life in harm’s way and to do the job.

That job, by America's most elite forces, is "direct action" -- combat missions that take the fight to the enemy, often including capturing or killing enemy combatants or commanders.

"I want to be here to conduct operations that benefit the people and destroy terrorism, but when immoral and illegal activities and actions are asked of me or [sic] ever going on with my knowledge then there is no reason for me to be here," wrote Roberts.

Top Green Beret Officer Forced to Resign Over Affair With WaPo Reporter

Gen David Petraeus on Disgraced Green Beret Legend: People 'Make Mistakes'

FULL COVERAGE: Jim Gant, Lawrence of Afghanistan

The Class of 2010 West Pointer, whose platoon was attached to a Green Beret operation Gant commanded, wrote that, "on multiple occasions I have suspected Maj. Gant of being intoxicated and under the influence of pain medications." Roberts added that while he once allegedly smelled alcohol on Gant's breath, he had never actually witnessed the alleged substance abuse.

Within days of Roberts filing the sworn statement to his company commander, Gant's camp in the village of Chowkay in Kunar province -- only miles from the porous border with Pakistan and under constant Taliban attack that month -- was subjected to an armed "health and welfare" search ordered by Combined Joint Special Operations Task Force commander Col. William Linn. Empty bottles for alcohol were discovered in Gant’s bunk.

He faced court martial for "dereliction of duty" but eventually accepted a severe general officer memorandum of reprimand, reduction in rank to captain, loss of his Special Forces tab and forced retirement in 2012 in a case that the Army kept hidden until his wife, former Washington Post reporter Ann Scott Tyson, published her book about Gant, “American Spartan,” in March. The reprimand cited Gant for allowing Tyson to live in his combat outpost for almost a year, as well as his painkiller and alcohol use in violation of General Order No. 1, the military code that lists prohibited activities for servicemen.

Though Gant admitted to the offenses, he and Tyson told ABC News they believe Gant’s critics in the military were using any excuse they could to force him out. Gant's Special Forces brethren had done what local Taliban commanders had only dreamt of -- they took him out of the fight and out of Afghanistan.

But Special Forces and other special operations veterans told ABC News unequivocally that Gant was hardly an exception.

"Pills and booze -- every A-camp," one combat-decorated, ten-deployment Special Forces soldier told ABC News, referring to the bases run by Operational Detachment-Alpha teams.

"They can get out of hand for sure. Most SF [Special Forces] dudes can still work but there are always the few that lose control and can't even function," agreed another Special Forces soldier with a dozen combat deployments, mostly in Afghanistan. "It is what it is: warriors dealing with s*** the public doesn't want to hear about or try to understand."

Special operations sources did not describe a secret culture of commando junkies but of operators who safely "self-medicate" to keep fighting at peak performance. Few in the U.S. military or government ever envisioned fighting through 13 years of combat deployments. All that time "downrange" plus training takes a physical toll.

An ABC News reporter visiting a large Special Operations camp in Afghanistan in 2010 was given Pakistani-labeled Xanax by an operator to help adjust to jet lag. Some operators use Ambien to sleep when they need to get rest and prescription amphetamines nicknamed "go pills" to stay awake and alert during combat operations.

"Downrange it's easy to get pills and safer than carrying around a bottle of booze," one special operations soldier said. "Our medic gave me two go pills before the longest patrol of my life. I was awake and going for over 48 hours."

When asked if he’d had experience with sleeping pills or stimulants while on deployment, another former Army special operations member said, “Yes, a lot.”

The former soldier said he and his team often worked on “reverse cycles,” meaning they were sleeping during the day and out on missions at night. Often Ambien was the only way to get rest during the daytime, though adrenaline always kept him up enough that stimulants weren’t necessary later. “Ninety-nine percent of the people taking it were responsible with it,” he said.

"I was issued Ambien on long flights. It was so you could hit the ground running," retired Green Beret Lt. Col. Jim Gavrilis, who served in Iraq, told ABC News. "Whether it's Red Bull or coffee to stay awake or Ambien, it's all in a spectrum of performance-enhancers so you can do the job and the mission."

There are multiple mentions of Ambien in “No Easy Day,” the book by a former member of the Navy’s elite SEAL Team Six, writing under the name Mark Owen, that detailed the mission to kill Osama bin Laden in May 2011. Owen writes that early one morning, just days before the historic mission, Owen “popped two Ambien.”

“No one was getting any rest without sleeping pills. No matter how much we tried to make this mission like the others, it wasn’t,” he writes.

Old combat wounds often cause pain, but so do other injuries sustained by training and extreme physical activity while hauling heavy kit -- a weapon in hand and ammo, radios, trauma kit, GPS unit and grenades on load-bearing vests in the front chest area for easy access. That weight distribution in front can bring back and neck injuries and painful knee problems, operators say.

"I self-medicated," Gant admitted in an ABC News interview. “I was in a lot of pain for a lot of different reasons, all of them combat-related. And I had to get through that. And [I] never said that I didn't do that. I did.”

As far as drinking in a war zone, another Special Forces commander, who knew Gant in Afghanistan, said it “absolutely” happens. “But people are held accountable.”

In 2010, two Green Berets and an Afghan interpreter -- who, according to a source who served with them, were smoking hashish though blood tests were lost and it was never proven -- went on a joyride in Khost and got into a shootout with Afghan security forces at a checkpoint. The interpreter was killed and the Green Berets were kicked out of the Army, as ABC News reported earlier this month.

One of the former special operations soldiers, who served multiple deployments in Iraq, told ABC News that drinking in moderation – “like a drink, maybe two” – was common while on deployment. “Except after the Saddam [Hussein] capture. We got housed,” he said.

It’s hardly a new phenomenon.

"We drank all the time in Vietnam -- the drug of choice was alcohol," Dick Couch, a former Navy SEAL and author of "Always Faithful, Always Forward" about Marine Special Operations, told ABC News. "We felt like we had a certain amount of entitlement."

Drinking downrange is a "leadership issue" and he added, "sometimes toward the end of a war we get a little raggedy-edged."

But usually the drinking and prescription medication use does not spill out into the open.

"It's not a problem if you're discreet about it," said a recently retired senior Special Forces officer.

Many of the sources said that medications are easy to get in Afghanistan because they are made cheaply in neighboring Pakistan. Alcohol also is easy to procure -- even in Iraq and Afghanistan -- and for many operators it helps them cope with post-traumatic stress disorder and sleeping disorders such as what Gant describes as afflicting him.

"General Order No. 1 is controversial. You're killing people. The American Army has always had alcohol to deal with the horrors of warfare," Gavrilis said.

But in a recent interview, Gant's accuser Roberts said he had a moral obligation to speak up about the Green Beret's substance abuse.

"I called my company commander and told him what's going on here. 'I suspect there's drugs floating around, strange behavior, and he's not telling his bosses what's going on.' He told me to put it down in a sworn statement," Roberts said.