MARINE CORPS BASE CAMP PENDLETON, Calif. -- They look innocent enough. A soda can lying on the side of a road. Maybe a lump of overturned dirt or even a war trophy to show off after a deployment. Problem is -- they're turning out to be one of the deadliest weapons Coalition forces face in Iraq.

They're called improvised explosive devices and they're largely to blame for many of the casualties inflicted on U.S. and allied troops on duty in Iraq. With Marines soon returning to the region, they too will have to face this often deceptive and sometimes undetectable tool of war.

"Improvised explosive devices are made on hand of readily available materials," said Master Gunnery Sgt. Samuel A. Larter, staff noncommissioned officer in-charge for 1st Explosive Ordnance Platoon with 1st Force Serce Support Group. "It is not a manufactured device like military munitions. They can be as simple or as complex as the builder decides."

FBI lends a hand

It's gotten so much attention, in fact, that the Federal Bureau of Investigation held a weeklong course at Marine Corps Air Station Yuma, Ariz., to show Marines the devastating effects of IEDs. Similar training was conducted here at Camp Pendleton and Marine Corps Air Station Miramar.

Special Agent Kevin G. Miles, a bomb technician with the FBI, has been training Marines in the explosive ordnance disposal field and in force protection billets alongside law enforcement officials.

According to Miles, the training teaches students to look for information that could lead to who made the bomb, what explosives were used and just what advanced technologies were used in the weapon.

"The students learn how to identify what kind of material was used in making a bomb, so they know what resources are available to the terrorists," Miles said.

As the weeklong course progressed, students received instruction on how to identify explosives, telltale signs they leave behind and the power they pack.

During the Yuma exercise, explosives ranging from dynamite to a homemade bomb were used to destroy a fuel tanker. The explosion caused collateral damage to one car parked to the side and to one parked in front of the large truck. Another explosion in the trunk of a car reduced it to a smoldering heap.

After examining evidence gathered from the burned debris, students pieced together what type of materials were used, how much was used -- and, most importantly, who did it.

"With this type of attack, students see that the first explosion is designed to lure Marines, law enforcement, or paramedics to the scene," Miles said. "A short time later the second bomb in the car, which is not parked far away, is detonated causing even more injuries."

Examples of IEDs

The truck bombing of the Marine barracks on Oct. 23, 1983, in Beirut, Lebanon, and the events of Sept. 11, 2001, are examples of IED attacks, Larter said.

"They run the spectrum from the most simple -- being basically a piece of pipe filled with a rapidly burning or explosive material and a piece of fuse stuck into it -- to the far end that would be an improvised nuclear device, a full-fledged thermonuclear bomb home built," Larter said. "The problem we run into in Iraq now is that everyone has free access to explosives and military ordnance because of all the caches and ammunition supply points that were abandoned during the war."

It's not just bomb-laden trucks, though.

Larter described some of the different IEDs that have been used in Iraq; not surprisingly, suicide vests were among the varied types.

"One of our teams recovered 280 of them (suicide vests) from a facility where they were making them in Iraq," Larter said.

Designed with 20 pounds of plastic explosive and lined with steel ball bearings, the leather vests "would have been devastating had they gotten out and been used," Larter said.

"The sheer amount of explosives and the way they packed the ball bearings, they had a giant, improvised claymore," he said.

Guarding against IEDs

Master Sgt. Michael R. Button, an EOD team leader with 1st FSSG, said many of the casualties occurred because forces in Iraq are letting down their guard.

"They have become predictable," Button said. "Their movements are all on major main supply routes and they are using the same ones over, and over and over."

"They are used to the point where these people are setting these things up, they are taking the time to bring in a broke-down vehicle to block a lane to channel them into a kill zone and these are all observed sites where they have somebody sitting a couple hundred yards away and when they see the military convoy coming along, they fire it (IED)," said Button.

"Any place in the world where they are using IEDs or vehicle IEDs is because whoever the target is has become predictable," he added.

It's common sense and attention to the surrounding area that Marines should rely upon to guard against IEDs, Button said.

"The big thing that most Marines are pretty good about because units are always briefing them is if it is not something you were issued, don't pick it up," Button said. "They know the Marines will want to take military hardware. Anything they think a guy is going to bend over and pick up and want to take with them, they run the risk of booby trap."

Gut instinct

"Trust your instinct. If you're in a situation where it doesn't feel right, it probably isn't," Miles added.

Unfortunately, children could be a sign of enemy presence.

"Americans don't look at children as part of the problem," said Gunnery Sgt. Rik L. Rarick, assistant operations and training chief for Marine Corps Base. "Like a drug dealer in New York, he is not going to go out and sell the drugs himself. He is going to use the kids, so even if they get caught, they cannot be prosecuted."

Most well-known to Marines, though, is the danger of redundancy and routine, which leads to predictability.

"If you develop a schedule, someone is going to pick up on it," Button stated. "As soon as you develop a pattern, you make yourself vulnerable".

It's a matter of keeping a sharp eye and a keen sense of awareness to guard against IEDs.

One of the most important resources Marines can use to stay alive is each other, Miles said.

"I was in Al Kut, my second night there ... my teammate and I were called out for a Russian hand grenade in a can filled full with gasoline," explained Gunnery Sgt. William W. Moore, an EOD team leader 1st Force Service Support Group, of the earlier stages of the war, "They had pulled the pin and the spoon was resting against the side of the can. The way they had put it there, it actually defeated itself."

With the spoon caught on the side of the can, "it didn't allow the striker to go home and set off the explosive train," Moore said. "It was a huge threat then and it has become more of a threat now. Iraq is an extremely dangerous place."