Erin Trieb for NBC News 22-year-old Chris Munoz, a private in the U.S. Army, refused to deploy to Afghanistan with his unit after claiming a crisis of conscience.

As his fellow First Cavalry soldiers stow their gear in Afghanistan, a 22-year-old Army private moves vehicles and cleans buildings at Fort Hood after declining to deploy on the grounds that his conscience won’t let him kill — a move resulting in fierce backlash within the military community.

Amid the era of the all-volunteer force and after 12 years of war, the “conscientious objector” application recently filed by Private Second Class Chris Munoz is a rarity compared to the 171,000 CO claims made during the divisive, draft-based Vietnam War. Only about 100 such claims are submitted annually, according to a federal report. But that number is rising, says a national organization that helps objectors.

“We are getting more calls. There seems to be a lot of folks having problems of conscience,” said Bill Galvin, counseling coordinator at the Center of Conscience & War, a Washington, D.C.-based advocacy group.

“When there’s conscription, we have a lot more work, certainly. But even these days, it's one thing in the abstract to say, ‘I'd like to defend my country,’ but it's something else entirely to be looking down at the barrel of gun and know you have that person’s life in your hands,” Galvin said. “Especially if you don’t know if that person is your enemy.”

Munoz, who is not granting interviews while Army commanders review his case, filed his claim on June 25, about 10 days before his unit deployed, said Lt. Col. Kirk Luedeke, a spokesman for the First Cavalry at Fort Hood. Rulings on CO claims may take as long as eight months. But, according to Munoz’s lawyer, the soldier’s feelings about warfare abruptly changed during basic training at Fort Benning, Ga., after enlisting on May 21, 2012.

“At weapons training, he really began to think about what he was being asked to do,” said James Branum, an Oklahoma City attorney who represents Munoz and several other CO applicants. “He was told there could come a situation where he might be forced to fire on a child. He realized then he could not fire upon a child, even if that child was a risk to him … That’s when things really clicked for him. That’s when he didn't believe anymore that he could kill.”

To gain a conscientious-objector discharge — and avoid a possible court-martial charge (and potential jail time), or to avoid a dishonorable discharge — Munoz filled out papers stating why he is opposed to all wars. He must convince the Army that his beliefs are sincere and shifted after his enlistment.

‘He didn’t have a choice’

According to his lawyer, Munoz revealed his changing attitude to his superiors at Fort Benning — and several subsequent times before he reached Fort Hood in April — but on each occasion, a higher-ranking solider suggested to Munoz that his case would be expedited if he simply waited to formally file it when he reached Fort Hood.

“We gave the command a few days to consider it. But once they decided, yes, he’s still going to deploy, that’s when we went to the press. Not an easy decision,” Branum said. “Not something a soldier ever wants to do. But really, he didn’t have a choice given the severity of the situation.”

"In good faith, the unit has left him here at Fort Hood while the process is being adjudicated," Luedeke said. "Chain of command has it, they’re aware of it. Once his packet goes through the procedural, the decision will be rendered and his status will be resolved."

While Munoz's lawyer carefully paints the gray nuances in the drastic mental shift of a once-committed enlistee — including the notion that, if sent to Afghanistan, Munoz would put himself and his unit at risk — his critics in the military community, especially those on social media, see the matter in purely black-and-white terms. According to Branum, his client has received "threatening emails."

At "Just The Tip of the Spear," a satirical website run by Marine veterans, the administrator contends that anyone who takes the pledge to defend this country should honor that vow "with every fiber of their being."

"For him to decide to leave his brothers before a deployment is deplorable. Any self-respecting member of the Armed Forces wouldn't be able to live with themselves for doing that," the site's administrator wrote in an email to NBC News. (The site's authors do not reveal their names.)

No simple decision

At "This Ain't Hell, but you can sure see if from here," a blog by Army combat veterans, Jonn Lilyea wrote in an email to NBC News that he has strong doubts about the sincerity of Munoz's CO claim.

"I've met some real COs and this guy, Munoz, doesn't seem to be one of them. It looks more to me that he doesn't want to be separated from his young family, which is fine, but it's NOT CO," wrote Lilyea, who retired from the Army in 1994 after serving in Desert Storm as an infantry platoon sergeant. He lives in West Virginia.

"Actually, me & most of my readers sympathize with real COs, we can appreciate true religious or philosophical opposition to war. Most of us have been to war and understand the feelings that arise from that experience. But, this Munoz guy hooks up with the anti-war vultures days before he's scheduled to deploy to make his case," Lilyea wrote.

At Fort Hood, Munoz has been treated fairly by other soldiers, his lawyer said.

But for leaders at the base, Munoz's case does not present a simple command decision, Luedeke said — nor does it carry an easy fix in the spirit of: 'He signed up for this, so he should just go to war,' as many of Munoz's detractors have asserted on social media.

"There’s always a bill to be paid by the leaders who have to consider the risk factors of having someone there (in Afghanistan) whose heart isn’t in it and who's maybe not fully dedicated to the mission," he said. "These are the types of factors that get considered."