iStock/Thinkstock(NEW YORK) — This week, Barack Obama became the first sitting U.S. President to visit the landlocked Southeast Asian nation of Laos. In making it his last stop on his last official trip to Asia, the President wanted to turn the page on this painful chapter of U.S. history.

During the height of the Vietnam War, the U.S. conducted another war in secret across the border in Laos in an attempt to destroy communist supply lines. More bombs were dropped on Laos than over Germany and Japan in World War II combined. Over the course of nine years, from 1964 to 1973, Laos became one of the most heavily bombed countries per capita in history.

However, 30 percent of the bombs dropped did not explode and to this day armed and active devices still litter the country. Since the bombings stopped, tens of thousands of Lao have been killed and maimed by these unexploded ordinances (UXO), and 40 percent of the victims are children.

One-third of the country is still contaminated by unexploded ordinances more than 40 years later, the ongoing cost of war that affects the Lao people daily.

As President Obama makes his historic visit, ABC Correspondent Bob Woodruff travels across Laos, meeting victims new and old and bearing witness the legacy left behind by America’s secret war.

Copyright © 2016, ABC Radio. All rights reserved.