For nearly a decade, Americans have been fighting - and dying - in Afghanistan. Just on Friday, three service members were killed in combat in the south.
Special Section: Afghanistan
Of the more than 1,000 U.S. deaths, nearly 40 percent were killed by improvised explosive devices, or IEDs for short. Preventing those attacks is job one for the Marines of the "Thundering Third," CBS News Correspondent Terry McCarthy reports.
IEDs are the hidden danger Marines fear the most.
Barely 100 yards from their base one day, a Marine patrol comes across an abandoned house booby-trapped with three IEDs. The Marines wired it for a controlled detonation, set a timer and run for their lives.
"They're either about 20 pounds apiece or 40 pounds, and we have found some that have been daisy chained," said Gunnery Sgt. Brian Smith of the 1st Marine Logistics Group.
Smith is particularly wary of daisy chains, where multiple IEDs are wired to go off at the same time. Smith, who is from Alabama, has been an explosives expert for four years. He knows how to find buried wires and pressure plates that detonate IEDs.
With four kids back home, Smith is only too conscious of the danger of IEDs. Now part of his job is to teach the other Marines in the 3rd Battalion, 1st Marine Regiment how to find them.
"You can place them anywhere around here, and we just do the best we can to train the Marines on where to look," Smith said.
There were 8,159 IEDs detonated or found in Afghanistan last year, an average of more than 20 a day. Marines have begun avoiding the heavily mined roads by driving through the desert, which is not without its own risks. On foot patrols, they stay off paths and footbridges, walking through the fields and wading canals instead.
This is one of the first Marine battalions to bring explosive-sniffing dogs to Afghanistan. They have 13 specially trained dogs.
Lance Cpl. Garrett Zeigler, a dog handler, grew up playing with dogs like dalmatians and German shepherds. Now he trusts a labrador named Dixie with his life.
"We click pretty well together," Zeigler said. "We make a good team."
The dogs can work 300 to 400 yards ahead of their handlers, so if they find an IED they can alert the Marines before they get into the danger zone.
But even the dogs are at risk. On May 6, a bomb-sniffing dog just north of here was killed by an IED, saving the lives of three Marines walking behind him.
"I'm sad; I'd be devastated if that were my dog," Zeigler said. "These dogs are there to protect Marines' lives, and that's what that dog did. The dog's a hero."
There are some threats the dogs cannot protect against. Just five weeks after speaking to CBS News, Zeigler was shot in the neck by a Taliban gunman. He survived but had to be evacuated to Germany.
That's a loss the Marines can barely afford. With IEDs so destructive and the Taliban planting new ones every day, the Marines need every tool they have to stay safe.
More Coverage of the "Thundering Third"
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