On March 18, 1969, the United States began a four year long carpet-bombing campaign in the skies of Cambodia, devastating the countryside and causing socio-political upheaval that eventually led to the installation of the Pol Pot regime.
During the Vietnam War, the Vietnamese Liberation Front and the PAVN used a network of supply routes that partially ran through Laos and Cambodia. As the War progressed, the U.S. ostensibly invaded both Cambodia and Laos in order to disrupt these routes.
The initial operation was authorized by then President Richard Nixon, but without the knowledge or approval of U.S. Congress. The bombings became public knowledge in 1973, after which they were stopped.
The United States dropped upwards of 2.7 million tons of bombs on Cambodia, exceeding the amount it had dropped on Japan during WWII (including Hiroshima and Nagasaki) by almost a million tons. During this time, about 30 per cent of the country's population was internally displaced.
Estimates vary widely on the number of civilian casualites inflicted by the campaign; however,as many as 500,000 people died as a direct result of the bombings while perhaps hundreds of thousands more died from the effects of displacement, disease or starvation during this period.
The Khmer Rouge, previously a marginalized guerrilla group, propagandized the bombing campaign to great effect; by the CIA's own intelligence estimates, the US bombing campaign was a key factor in the increase in popular support for the Khmer Rouge rebels. After their victory in 1975, the Khmer Rouge oversaw a period in which another one-to-two million Cambodians died from execution, hunger and forced labour.
After it became public, the bombing campaign was a subject of contention within the U.S. as opposition to the U.S. military project in Indochina intensified.
"Manufacturing Consent" Noam Chomsky and Edward S. Hermann