A little-known anniversary passed by on April 17. On that day in 1975, Cambodian politician Saloth Sâr – better known by his nom de guerre, Pol Pot – began the Cambodian Genocide, one of the deadliest mass murders of the late 20th century, claiming the lives of between 1.5 and 2 million people.

Naturally, this event has been of some national significance in Cambodia, with vigils throughout the country to honor the dead and missing. In the United States, there is no such reverence. Why should there be? Why should we mourn the actions of a murderous dictator half a world away? The question has two answers; the first and more obvious answer is that all humans should mourn any major loss of human life, regardless of national boundary. The second – one that requires slightly more explanation – is that the United States was directly responsible for the ascendancy of Pol Pot and the unprecedented misery that followed.

“Anything that flies on anything that moves.” This was the phrase that put Cambodia on the course to genocide. It was an order uttered by former U.S. Secretary of State Henry Kissinger during much of the Vietnam War, which set into motion a series of American bombing campaigns on much of Cambodia between 1969 and 1973. Kissinger, along with former U.S. President Richard Nixon, originally developed the campaign to counteract members of the National Liberation Front (better known in the United States as the Viet Cong), who were using large portions of Cambodian territory as conduits to targets in South Vietnam. Later bombings were rationalized in defense of the Cambodian government of Cambodian politician Lon Nol against the growing Khmer Rouge movement, as well as against looming intervention from North Vietnam. The bombings resulted in the deaths of between 50,000 and 150,000 Cambodians, as well as irreparable damages to infrastructure, private residences, sanitation amenities, and other property within the already-poor country. An additional 2 million refugees – about a quarter of the Cambodian population at that time – were displaced by the bombings.

Likely the most tragic aspect of this savage, spuriously-reasoned bombing campaign was that it actually bolstered the Khmer Rouge’s cause within Cambodia. Director of the Yale University Genocide Studies Program Ben Kiernan noted that “the CIA’s Directorate of Operations, after investigations south of Phnom Penh, reported in May 1973 that the communists were successfully ‘using damage caused by B-52 strikes as the main theme of their propaganda’” against the Lon Nol government, concluding that “the U.S. carpet bombing of Cambodia was partly responsible for the rise of what had been a small Khmer Rouge insurgency, which now grew capable of overthrowing the Lon Nol government, and once it had done so in 1975, perpetrating genocide in the country.” Kiernan is not the only scholar to assign blame with U.S. artillery; several studies of Khmer Rouge approval during the time of the bombings concluded that they “[were] counterproductive” and “hampered the pacification campaign” occurring within Southeast Asia.

It would be difficult to argue that the subsequent malnutrition, forced labor, and killing fields that followed Pol Pot’s accession were purposely designed or directed by American officials; some blame can reasonably be shouldered on the Khmer Rouge government. But there is no doubt that, in nearly extirpating the nation’s countryside of shelter, infrastructure, and lives, Kissinger and Nixon found Cambodia of marble and left it of clay. And Pot molded that clay into the tyrannical, murderous regime that instigated the genocide. Perhaps a vigil is in order.