From 1964 to 1973, the U.S. dropped over 2 million tons of bombs in Laos, making it the most heavily bombed country per capita in history. This secret war had a devastating impact on civilians. It wasn't until 1997 that the U.S. officially acknowledged this covert operation. How did the CIA keep its largest-ever paramilitary mission hidden for two decades? Why did they wage a secret war in Laos?