Air America planes carried drugs during the CIA's secret war in Laos, though there is debate about whether Air America and the CIA were actively involved or merely allowed others to transport drugs. During this war, the CIA used the Meo (Hmong) population to fight Pathet Lao rebels. Because of the war against Pathet Lao rebels, the Hmong depended upon poppy cultivation for hard currency. The Plain of Jars had been captured by Pathet Lao rebels in 1964 which resulted in the Laotian Air Force not being able to land their C-47 transport aircraft on the Plain of Jars for opium transport. The Laotian Air Force had almost no light planes that could land on the dirt runways near the mountaintop poppy fields. Having no way to transport their opium, the Hmong were faced with economic ruin. Air America was the only airline available in northern Laos. "Air America began flying opium from mountain villages north and east of the Plain of Jars to Gen Vang Pao's headquarters at Long Tieng."