At the time, its architects expected the war to be short. Removing Saddam Hussein — whom the US falsely accused of harboring weapons of mass destruction and supporting al-Qaeda — was the stated goal. Few considered the possibility that, in one form or another, the conflict could drag on for well over a decade. And certainly none of them considered the impact that 13 years of war could have on Iraqi youth.

The lives of Iraqis now in their late teens and twenties have been shaped by years of Western economic sanctions, the US invasion, and the conflicts that were at least partly born from it: multiple insurgencies, civil war, and the rise of ISIS. The paths of young people have been altered in life-changing ways. And as Iraq's 20 million children grow to be adults, their experiences will shape the country — for better or for worse — for many years still to come.

"There is so much research now on how it changes the brain," says Johanna Van Grinsven, a psychologist with Doctors Without Borders based in neighboring Jordan. Studies show how exposure to trauma can rewire the brain of a child, often halting social or emotional development and the ability to learn. "I think the main part is an inability to feel safe, both in an external world and in an internal world."