Behind the front lines with a U.S. soldier training Iraqi troops

BAGHDAD -- ISIS suicide bombers killed at least 17 Iraqi soldiers Thursday outside the city of Ramadi.

U.S. troops have been training the Iraqi army for 13 years. It's cost American taxpayers nearly $30 billion -- with no end in sight.

U.S. troops try to bring Iraqis up to speed -- fast

On the outskirts of Baghdad, Iraqi army recruits take aim at an imaginary enemy. But U.S. trainer Sgt. First Class Josh McSpadden knows it's all too real.

He's been here before, during the worst of the fighting in 2004, and he remembers in vivid detail the day he thought he was going to die.

"It was the only day in my life that I ever thought I wasn't going to make it home alive," McSpadden told CBS News. "It was so intense. So intense."

And now, McSpadden is back in Iraq.

"It's frustrating," he said. "You want to see your brothers in arms, the Iraqi people, have the same motivation, fight the same way that you do. And really, just to come back here and face the same problems, you know -- when is enough going to be enough?"

He doesn't have a lot to work with -- a rusty Russian tank and a handful of armored personnel carriers. There's not enough ammunition to practice with the big guns.

They're not much, but they'll be vital in any ground offensive Iraqi forces launch against ISIS, and it's no exaggeration to say that the recruits are far younger than any of the tanks they'll be firing.

ISIS launches multiple suicide attacks in Baghdad

On Wednesday, the Iraqi capital suffered the worst bloodshed the city has seen this year with three ISIS bomb attacks.

McSpadden says that only strengthens the resolve of his new recruits.

"They're very motivated, especially with the attacks that happened in Baghdad -- that angers them, and they want to take their cities back," he said.