The insurgency in Iraq requires a new kind of discipline, according to David Perinchief. "You can be handing out pens, pencils, medical supplies, being nice — then you can see a car coming at you really fast and be in a full-blown firefight, and you have to transition instantly. "You have to differentiate between the guy who is carrying a weapon, and the guy who is actually shooting at you.

"You have to understand when people need help, even if they are not asking for it; and when people really do not want you there.

"You have to understand that every action has a reaction. That's why I'm really proud of my Marines. They never did anything malicious."

Every person encountered must be treated humanely, he said — for if they were not insurgents before, mistreatment at the hands of the US Military will certainly turn them in to insurgents. "That's where the training comes in: your ability to control yourself in a truly horrifying situation."

After completing a period in Afghanistan chasing down the Taliban, Sgt. Perinchief entered Iraq for the first time as an infantry squad leader in mid-March, 2006 with the 3rd Battalion, 3rd Marines, 3rd Marine Regiment.

The specific role of his unit was to take over from the unit accused of perpetuating a massacre in Haditha in late 2005. According to media reports, Haditha was completely controlled by insurgents and visited only occasionally by US troops. According to Sgt. Perinchief, by the time his unit left, Iraqi security forces were in complete control.

Focusing solely on Haditha, Sgt. Perinchief said he could not speak to the sectarian violence currently tearing apart the city of Baghdad, some 240km to the southeast. The insurgents in Hadith were mostly kids, he said — the youngest he knew of being 14 - and were mostly driven not by political or religious conviction, but by money.

The tasks faced in Iraq, he added, were completely different to those he faced in Afghanistan.

"You're working 120 hours a week, minimum. You're constantly going outside the wire, you're eating whatever you can whenever you can, you're taking catnaps every chance you get, you're always moving, you're always on patrol. It's non-stop for seven months.

"You're in firefights, you're filling sandbags, you're researching terrain, you're reinforcing walls, you're ensuring your guys are briefed, you're focusing on the rules of engagement, you're learning routes through the city, you're training for what happens if someone goes down, if violence escalates. It's a never-ending cycle.

"If you slack off, you're going to get hurt."

You are also, he said, making contact with Iraqis: both civilians and security forces.

Though the Marines are not taught much about Islam, he said that much emphasis is placed on understanding the Iraqi culture. "You are in contact with civilians every day.

"They teach English, so most of the population speaks it, even if they act like they don't. It's a very family-oriented culture.

"I have no problem with the Iraqi people," he said, adding that the only frustration comes when Iraqis withhold information for fear of retribution. "Then again, if someone's threatened to kill your entire family, I can understand you holding back on information too."

The civilians, he added, find the US military presence in Iraq routine — at least, the ones in Haditha did. Insurgents in Haditha, he added, were not motivated by political or religious conviction, but by money.

As for the Iraqi security forces he trained: "We have such a strong relationship with the soldiers.

"The guys we had cared. They wanted to be there. It's difficult to find people who want to protect Iraq — freedom is a new concept, for them it's hard to understand.

"And they are just as interested in us. By the time we left we had a great relationship — hanging out, playing cards."

Iraq is not an easy place to survive, he said. Fear, however, never played a large part for his men. "I never heard my Marines complain. We'd have days with no food, little water, and they'd just deal ... I stand in awe of what my guys were willing to go through.

"It's an all-inspiring event, seeing what your fellow man is willing to do for you in combat."

There are definitely frustrations, he said. Those frustrations, however, are the every day facts of life: stress, fatigue, hunger. "We're just bombarded with more of it.

"I was exhausted, frustrated, angry. I took a step back — you have to know when to fight for your men to have a break. I'd tell the commander that my guys need six straight hours of sleep and he'd give it — then they'd wake up and be gone again. It's unbelievable, what these guys will do."

Now on 20 days leave, Sgt. Perinchief said he is unsure where he will be deployed next.

However, he added, "If I'm told to go back to Iraq, I'll go. If I'm ordered to go back to Afghanistan, I'll go."

"I'm lucky to have found my niche in life ... This is what I am good at. I am proud of what I do."