WASHINGTON -- In the chaos and heat and noise of combat, weapons and ammo and manpower are all important -- but one critical intangible is trust.

Sergeants hammer it into their young troops: "Do the right thing when no one is watching."

As spreading scandal enfolds two of the military's most respected leaders, retired Army Gen. David Petraeus and Marine Gen. John Allen, there is growing concern that the appearance or reality of senior leaders not "doing the right thing" will have a damaging effect on a military that relies so heavily on trust.

Petraeus has acknowledged an extramarital affair, and senior officials have confirmed the relationship with his biographer, Paula Broadwell, after Petraeus retired from the Army in order to become CIA director in September 2011. Allen, currently the top U.S. and allied commander in Afghanistan, was set to become NATO commander. His nomination was put on hold after the FBI uncovered thousands of potentially inappropriate emails between the general and Tampa, Fla. socialite Jill Kelley.

The sudden fall from grace of two of the nation's most admired leaders has sent shock waves deep into the military ranks, where the bond of trust is considered almost sacred.

In combat, said a former battalion commander who asked for anonymity to discuss ethics related to the current scandal, "everything moves so fast and the stakes are so high and you don't have a lot of time, that's when it's critical that you have built that layer of implicit trust -- trust that you are going to drive on and do the right thing. And most people do."

That trust gives combat leaders confidence that their subordinates will strive to carry out the mission -- will go out and do the right thing -- and their subordinates trust that their leaders actions are tactically and morally sound.

The ethic of trust is not one of the seven Army values, which include honesty, integrity and physical courage, and are emblazoned on the dog tags given to each recruit. But formal ethics instruction is part of military education from basic training on up through the services' war colleges. But the shorthand version -- doing the right thing when no one's watching -- is demanded on a daily basis, and has become the foundation for the military's operations in Iraq and Afghanistan.

"Warfare has become more and more decentralized -- we've seen younger soldiers get more and more responsibility, expected to operate as if they are being directly supervised but, frankly, they are not," said Paul Eaton, a retired Army major general. In 30 years of active duty, Eaton was the Army's chief of infantry and was responsible for training the Iraqi army in 2003 to 2004.

The scandal brewing with Petraeus and potentially with Allen, Eaton said, "is a big deal. When your very senior people commit serious offenses and you're a young sergeant or a young officer trying to teach 18-year-olds the morality and ethics that we expect of them, it's a big deal.

"Do we have a problem with creeping cynicism? It's a little early to tell, but every time something like this happens it has a corrosive effect on the entire force," he said.

But is it fair to apply the military's combat ethic to peacetime? From what is known publicly, Petraeus did not begin the affair until he retired from active duty. And some believe it has been a mistake for the military to claim such a high standard anyway.

"I think we overpromised and now we are under-delivering," said a former infantry officer who asked not to be identified because he continues to serve in a sensitive position.

"These are not standards that are are held by anyone else -- certainly not by elected officials, or Congress, or even the president. We have over-sold our ethics in a self-righteous way above our civilian counterparts," he said. "We oversold our ethics, and now we need to scale that back."

But Eaton disagreed. "We are an institution that uses lethal force and that takes on substantial risk, so we are held to a higher standard," he said. "That higher standard must be maintained, must be enforced through very harsh accountability measures."

Drill sergeants, the legendarily tough men and women responsible for immersing recruits in military culture, are unyielding on ethics.

"There's a certain standard that's put out there and they are expected to meet that, and if they don't, to fix the problem," said Army Staff Sgt. Jeffrey Heilman, 29, the Army's active-duty drill sergeant of the year. "It's as simple as being held accountable for everything you do."

"With my soldiers I try to explain to them, it's easy to do the right thing when the drill sergeant is watching. When they leave, I want them to remember, 'Hey -- the drill sergeant taught me to do the right thing and now no one's looking, and I need to do the right thing,'" said Staff Sgt. Jarod Moss, 30, of Dallas. Moss is the Army reserves drill sergeant of the year.

"At the end of the day," Moss said, "everybody has to look in the mirror and ask if I did the right thing today."

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