Despite being close allies before the Khmer Rouge came into power, there were deep and divisive historical tensions between Vietnam and Cambodia. The Khmer Krom were at the heart of that mutual mistrust.
The Khmer Krom are the “lower Khmers”—Cambodians of the lower Mekong delta region or Khmer Kampuchea Krom. Historically, they had distinct surnames, different accents from other Khmers and nuanced cultural practices that set them apart. But in 1949, that territory was transferred by the French colonial government to Vietnam and was re-named An Giang.
During this time, the Khmer Krom formed a pro-independence, anti-communist movement called the Khmer Serei. Following independence, a new movement called the White Scarves sprung up and they focused their efforts on trying to reclaim their territory from the communist Vietnamese.
In the context of the Indo-China wars which involved international actors like the U.S., China and Russia, the Khmer Krom were perfect recruits for the American forces fighting against the communist Vietnamese. They had geographical familiarity with the border areas and many could speak Vietnamese; they could handle protracted guerilla warfare; and they showed an ability to forge strategic allegiances to fight for their cause.
Along with several indigenous and ethnic minority groups, many Khmer Krom were enlisted into the Civilian Irregular Defense Group (CIDG), a U.S. government programme that was created during the war to fight against the communist Vietnamese forces. That made them traitors and enemies in the eyes of the Khmer Rouge—literally Central Intelligence Agency (CIA) “spies”. In one instance, 68 Khmer Krom soldiers crossed the border into Cambodia and asked to see Khieu Samphan, in the hopes of joining the Khmer Rouge to fight against the Vietnamese. Their leader was taken to Tuol Sleng, where he was tortured and executed. The remaining 67 were gunned down. Sometimes, they were identified merely by the fact that they had long hair and drank milk: the drink of western imperialists.
Yet, it was their malleable identities that made the Khmer Krom easy enemies of the Khmer Rouge. The fact that they spoke Vietnamese and blended with the “enemy” meant they were not just American spies. They seemed Khmer, but they were, in fact, Vietnamese. Khmer bodies with Vietnamese minds.
So, Regulation 8 at Tuol Sleng came to refer to both the Khmer Krom and the Vietnamese. Both were enemies, their fates interwoven.