I swear I heard Bourdain talk about this in an episode from one of his series. The laos episode hits on the topic, but the Cambodia episode is only available for pay.
Laos (Start at 32:50): https://www.youtube.com/watch?v=A1s8jntlpK0
Shamelessly stolen from reddit, quoted from a broken link from Yale:
The still-incomplete database (it has several “dark” periods) reveals that from
October 4, 1965, to August 15, 1973, the United States dropped far more ordnance on
Cambodia than was previously believed: 2,756,941 tons’ worth, dropped in 230,516 sorties on
113,716 sites. Just over 10 percent of this bombing was indiscriminate, with 3,580 of the
sites listed as having “unknown” targets and another 8,238 sites having no target listed at
all. The database also shows that the bombing began four years earlier than is widely
believed—not under Nixon, but under Lyndon Johnson.
The impact of this bombing, the subject of much debate for the past three decades, is now
clearer than ever. Civilian casualties in Cambodia drove an enraged populace into the arms
of an insurgency that had enjoyed relatively little support until the bombing began,
setting in motion the expansion of the Vietnam War deeper into Cambodia, a coup d’état in
1970, the rapid rise of the Khmer Rouge, and ultimately the Cambodian genocide.
In video form:
https://www.youtube.com/watch?v=BZpKFBTutW8