A year and a half after U.S. troops withdrew following a protracted war they didn't win, Iraq could be headed for a slide back into civil war. Now, American veterans are wondering whether their service there, and that of the 4,486 U.S. troops who lost their lives, was worth the cost. They're also wondering what impact the country's descent into violence could have on U.S. troops who are now serving in Afghanistan, after previously serving in Iraq. The nagging questions about whether the war was worth it, some troops say, could deepen the mental health scars the conflict has already left behind. "You think about the guys who lost their lives in World War II, at least there was a higher purpose for risking your life," one vet who survived an IED blast in Iraq and later attempted suicide said. "Now that I’m hearing about this, all I think about is the guys we lost in Iraq. It’s hard to not think that it meant nothing."